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October 6, 2026 · 4798 words

7 Canonical Tag Rules Every Site Needs for SEO Success

Master SEO with 7 essential canonical tag rules! Learn how to prevent duplicate content issues, consolidate link equity, and improve crawl efficiency for you...

Digital path branching, one path marked primary, other paths redirecting

Every website needs to implement seven essential canonical tag rules to manage duplicate content, consolidate link equity, and improve search engine crawl efficiency effectively. Following these rules ensures search engines understand your preferred content versions, preventing issues like diluted ranking signals and wasted crawl budget.

Canonical tags are fundamental to a healthy SEO strategy. They guide search engine crawlers. They clarify your preferred URLs for indexing. They impact how your content ranks and performs.

  • Define canonical tags. These HTML elements or HTTP headers indicate the preferred version of a web page among a set of duplicate or very similar pages.
  • Explain their purpose. Canonical tags prevent duplicate content issues, consolidate link equity, and ensure search engines index and rank the correct version of your content.
  • Impact SEO. Proper canonicalization protects your search rankings, improves crawl efficiency, and prevents search engines from splitting ranking signals across multiple URLs.

Key Takeaways

Point Details
Canonical Tag Purpose Canonical tags (rel="canonical") inform search engines which URL is the preferred or "canonical" version when multiple URLs display identical or very similar content. This prevents duplicate content penalties and consolidates ranking signals.
Implementation Basics Always use absolute URLs. Implement self-referencing canonicals on every page. Ensure canonicals point to the preferred version, resolving HTTP/S, www/non-www, and trailing slash issues.
Common Pitfalls Avoid canonicalizing to 'noindexed' pages or chaining canonicals. Do not use canonicals as a substitute for 301 redirects. Monitor your canonicals regularly to catch errors.
Google's Perspective Google treats canonical tags as hints, not directives. While Google usually respects your choice, it may occasionally choose a different canonical URL if it deems it more appropriate, particularly due to technical errors or conflicting signals.
CitedGiraffe's Role Proper canonicalization forms the technical foundation for effective content strategy. CitedGiraffe's AI-powered content platform relies on a technically sound website to ensure your high-quality, optimized content reaches its target audience without technical impediments.

Table of Contents

Understanding Canonical Tags: What They Are and Why They Matter

A canonical tag, also known as rel="canonical", is an HTML link element that tells search engines which version of a URL is the definitive or "canonical" version. You place this tag in the <head> section of a web page. Its primary purpose is to address duplicate content issues. When search engines encounter multiple URLs with identical or very similar content, they need a clear signal to determine which URL to index and rank. Without this signal, search engines may struggle to decide, potentially diluting link equity and wasting crawl budget. This can negatively impact your search engine rankings.

Duplicate content arises from various factors. These include URL parameters for tracking, faceted navigation on e-commerce sites, printer-friendly pages, or different HTTP/HTTPS and www/non-www versions of your site. Canonical tags help consolidate ranking signals from all duplicate versions into a single, preferred URL. This ensures your most important content receives the full benefit of inbound links and other ranking factors.

Rule 1: Always Use Absolute URLs for Your Canonical Tags

When implementing canonical tags, you must use absolute URLs. An absolute URL includes the full protocol (HTTP or HTTPS), domain name, and path. For example, use https://www.example.com/page/ instead of /page/. Relative URLs can lead to misinterpretations by search engines, causing them to ignore your canonical tag or incorrectly apply it to unintended URLs. This can severely undermine your canonicalization efforts.

Google Search Central explicitly recommends using absolute URLs for canonical tags. A relative URL might be parsed differently depending on the context in which a crawler encounters it, leading to unpredictable and incorrect canonical assignments. Always provide the complete and unambiguous path to your preferred URL.

<link rel="canonical" href="https://www.example.com/your-preferred-page/" />

This is the correct format. Avoid:

<link rel="canonical" href="/your-preferred-page/" />

Using absolute URLs ensures clarity and consistency across all search engine interactions with your site.

Pro tip. Implement a consistent URL structure across your entire website. This means deciding on HTTP vs. HTTPS, www vs. non-www, and trailing slashes. Then, enforce these decisions in your canonical tags, internal links, and sitemaps. Tools like CitedGiraffe can scan your site to help identify inconsistencies in your URL structure before they cause SEO issues.

Multiple web pages, one highlighted as original with arrow pointing
Consolidating duplicate content to a single, authoritative source.

Rule 2: Implement a Self-Referencing Canonical Tag on Every Page

Why Self-Referencing Canons Are Essential

A self-referencing canonical tag is a canonical tag on a page that points to its own URL. For example, if your page is located at https://www.example.com/page-a/, its self-referencing canonical tag would be <link rel="canonical" href="https://www.example.com/page-a/" />. This practice is a best practice recommended by Google and other SEO experts. It explicitly declares your intention for that specific URL to be the canonical version, even if no obvious duplicates exist.

Self-referencing canonicals prevent unintended canonicalization issues. Minor URL variations, like those with session IDs, tracking parameters, or slight ordering differences in parameters, can inadvertently create duplicate content. A self-referencing canonical proactively guards against these potential issues, solidifying your preferred URL choice for search engines. It reinforces the authority and uniqueness of that specific page.

How to Implement a Self-Referencing Canonical

You place the self-referencing canonical tag within the <head> section of your HTML document. Ensure the URL specified in the href attribute is the absolute, preferred version of that page. Most modern Content Management Systems (CMS) like WordPress (with plugins like Yoast SEO), Shopify, or Squarespace, automatically add self-referencing canonicals. Always verify this implementation.

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Your Page Title</title>
    <link rel="canonical" href="https://www.yourdomain.com/your-page-slug/" />
    <!-- Other head elements -->
</head>
<body>
    <!-- Page content -->
</body>
</html>

Double-check your CMS settings to ensure it generates these tags correctly and consistently across all your pages. Any page without a self-referencing canonical, or with an incorrect one, creates ambiguity for search engines.

Rule 3: Canonicalize Only to the Preferred Version of a Page

Your canonical tag must always point to the single, preferred version of a page. This includes resolving variations related to protocol, domain, and URL structure. Inconsistent canonicalization sends mixed signals to search engines, potentially leading to indexing issues and diluted ranking power.

Handling HTTP vs. HTTPS and www. vs. non-www.

Modern websites should universally use HTTPS. If your site serves content over both HTTP and HTTPS, or both www. and non-www. versions, you must consolidate these. For example, if your preferred version is https://www.example.com/page/, then http://www.example.com/page/, https://example.com/page/, and http://example.com/page/ should all canonicalize to https://www.example.com/page/. The best practice is to implement 301 redirects from all non-preferred versions to the preferred HTTPS www. or non-www. version. For any pages that cannot be redirected, use a canonical tag to point to the preferred URL.

Pro tip. Perform a site-wide audit for mixed content (HTTP resources on HTTPS pages) and consolidate all URLs to HTTPS. This improves security and SEO. Google favors HTTPS sites, and a consistent protocol across your canonicals is crucial. Utilize HTTPS for all internal links as well.

Dealing with Trailing Slashes and URL Parameters

Decide whether your preferred URLs will end with a trailing slash (e.g., https://www.example.com/page/) or not (e.g., https://www.example.com/page). Stick to this convention consistently. If your preferred URL includes a trailing slash, then any version without it should canonicalize to the version with it. The same logic applies if you prefer no trailing slash.

URL parameters, often used for tracking (e.g., ?utm_source=email), sorting (e.g., ?sort=price), or filtering (e.g., ?color=blue), frequently create duplicate content. For instance, https://www.example.com/products/widgets?color=blue and https://www.example.com/products/widgets might display very similar content. In such cases, the parameterized URL should canonicalize to the cleaner, non-parameterized version: https://www.example.com/products/widgets. This prevents search engines from indexing multiple URLs for essentially the same content, consolidating ranking signals.

<link rel="canonical" href="https://www.example.com/products/widgets/" />
<!-- on a page like https://www.example.com/products/widgets/?color=blue -->

Rule 4: Avoid Conflicting Canonical Signals

Conflicting canonical signals confuse search engines and can render your canonical tags ineffective. Ensure all signals point to the same preferred URL. This includes the rel="canonical" tag, internal links, sitemaps, and any 301 redirects.

Don't Canonicalize to a 'Noindexed' Page

Never point a canonical tag to a page that is blocked from indexing using a noindex meta tag or an HTTP X-Robots-Tag: noindex header. A noindex tag tells search engines not to index a page, while a canonical tag tells them which page to index. These two directives contradict each other. Search engines will typically prioritize the noindex directive, meaning the canonical target page will not be indexed, and the link equity from the canonicalizing page will be lost or not consolidated effectively. This is a common and critical error.

According to Google Search Central's documentation on duplicate URLs, "Do not point the canonical URL to a 'noindexed' URL. That's a strong contradiction; the canonical would be ignored."

Don't Chain Canonicals (A→B→C)

Avoid creating canonical chains, where Page A canonicalizes to Page B, and Page B then canonicalizes to Page C. Search engines might ignore such chains or only follow them for a limited number of hops. This dilutes the signal and makes it harder for search engines to determine the ultimate canonical URL. Always point the canonical tag directly to the final, preferred URL. If Page A, B, and D all display similar content and Page C is the preferred version, then Page A, B, and D should all canonicalize directly to Page C. This ensures clarity and efficiency for crawlers.

A chain involving 3 or more canonical hops (e.g., A → B → C) introduces unnecessary complexity and potential for misinterpretation by search engines. Direct canonicalization is always preferred.

Rule 5: Use Canonical Tags for Duplicate Content, Not as a Redirect Alternative

Canonical tags and 301 redirects serve different purposes, although both deal with multiple URLs for similar content. A canonical tag is a hint to search engines; it does not physically redirect users or crawlers. Users can still access the non-canonical URL. A 301 redirect is a permanent server-side instruction that sends both users and search engine crawlers from one URL to another. The original URL becomes inaccessible or redirects to the new one.

You use canonical tags when you want to keep duplicate or similar pages accessible to users (e.g., product pages with different sorting options, or syndicated content) but tell search engines to only index one version. You use 301 redirects when a page has permanently moved, or you want to entirely consolidate two distinct pages into one, removing the old URL from circulation. For example, if you change your domain name or merge two blog posts, a 301 redirect is appropriate. If you have two nearly identical product pages for different regional markets, a canonical tag might be better if you want both pages to be discoverable but only one indexed per region.

What it is not: A canonical tag is not a technical redirect. It does not transfer users from one URL to another. It only passes a signal to search engines about URL preference.

Rule 6: Leverage Canonical Tags for Cross-Domain Duplicates and Syndication

Canonical tags are not limited to a single domain. You can use them effectively to manage duplicate content across different domains, particularly in content syndication scenarios. This is a powerful feature for content creators and publishers.

When you publish your content on multiple domains, perhaps through partnerships or content distribution networks, using a canonical tag is crucial. It tells search engines which original source URL should receive the primary link equity and ranking credit. Without this, the link equity from backlinks to the syndicated versions could be diluted across various domains, diminishing the SEO value for the original content creator. By pointing all syndicated versions to your original domain, you ensure that the SEO benefits are funneled back to your authoritative source.

Best Practices for Syndicated Content

If you syndicate your content, ensure the publishing partner includes a rel="canonical" tag on their version of the article, pointing back to the original article on your website. This practice is widely accepted and respected by search engines. The W3C's documentation on rel='canonical' HTTP Headers acknowledges cross-domain canonicalization. This helps preserve your site's authority as the original publisher. When syndicating content, clarify these technical requirements with your partners to avoid duplicate content penalties.

<!-- On the syndicated article page -->
<link rel="canonical" href="https://www.youroriginalsite.com/original-article-url/" />
Conflict: arrows pointing away from each other on digital map
Avoid sending mixed signals to search engines about your preferred page.

Rule 7: Monitor and Audit Your Canonical Tags Regularly

Canonical tags are not "set it and forget it" elements. Websites evolve, content changes, and technical issues can arise. Regular monitoring and auditing of your canonical tags are essential to ensure they remain correct and effective. Incorrect canonicals can lead to significant SEO problems, including loss of organic visibility and ranking drops.

Tools for Canonical Tag Auditing

Several tools can help you audit your canonical tags:

  • Google Search Console: This is your primary source of truth. Under the "Pages" or "Index Coverage" reports, Google reports which URL it has chosen as canonical for your content. It also highlights "Duplicate, Google chose different canonical than user" issues.
  • SEO Crawlers: Tools like Screaming Frog SEO Spider, Ahrefs Site Audit (which you can check at Ahrefs' guide to canonical tags), or Semrush Site Audit can crawl your website and identify canonical tags, report missing or incorrect implementations, and detect canonical chains or conflicts.
  • Browser Extensions: Extensions like "Canonical Tag Checker" or "SEO Minion" can quickly show you the canonical tag of any page you visit in your browser.

Plan to perform a full canonical audit at least quarterly, or after any major website migration, redesign, or content overhaul. For larger sites, consider monthly spot checks on critical pages.

Common Canonical Tag Mistakes to Look For

  • Missing Canonicals: Pages that should have a canonical tag but don't.
  • Incorrect Canonical Target: A canonical tag points to the wrong page, a 404 page, or a non-existent URL.
  • Noindexed Canonical Target: As discussed, a canonical pointing to a page that is also noindexed.
  • Chained Canonicals: Page A canonicalizes to Page B, which then canonicalizes to Page C.
  • HTTP/HTTPS or www/non-www Mismatches: The canonical points to a different protocol or subdomain than the preferred version.
  • Canonicalizing Paginated Series: Each page in a paginated series should self-canonicalize, not canonicalize to the first page.

Common Scenarios Where Canonical Tags Are Crucial

Canonical tags are essential in many everyday website operations. Understanding these scenarios helps you apply the rules effectively.

E-commerce Product Pages with Variants

E-commerce sites frequently generate multiple URLs for the same product based on variations like color, size, or sorting options. For instance, /product-a?color=red, /product-a?color=blue, and /product-a?sort=price might all display nearly identical content for "Product A." In such cases, all these variant URLs should canonicalize to the main product page, e.g., /product-a. This consolidates all ranking signals to the core product page, preventing internal duplicate content issues.

Some e-commerce platforms like Shopify automatically handle canonicals for product variants, but always verify their implementation. You might need to adjust settings or use specific apps to fine-tune this for complex product structures.

Pagination and Filtered Navigation

Pagination (e.g., /category?page=1, /category?page=2) and filtered navigation (e.g., /category?filter=brand-x) also create URLs with similar content. For paginated series, each page should typically self-canonicalize. You should not canonicalize all paginated pages to the first page of the series, as this might cause search engines to ignore subsequent pages. For filtered navigation, you usually canonicalize the filtered pages to the main category page, assuming the filtered content is a subset or slight variation of the main page. Alternatively, if filtered pages offer unique value, they might self-canonicalize.

For example, if https://www.example.com/blog/category/seo/page/2/ is a paginated page, its canonical tag should be <link rel="canonical" href="https://www.example.com/blog/category/seo/page/2/" />. However, if https://www.example.com/products/shoes/?brand=nike is a filtered page, it might canonicalize to https://www.example.com/products/shoes/.

Printer-Friendly Pages and Session IDs

Older websites or specific content management systems might generate printer-friendly versions of pages (e.g., /article?print=true) or URLs with session IDs (e.g., /article?sessionid=xyz). These are classic examples of duplicate content. All such URLs should canonicalize to the clean, core version of the page (e.g., /article). Modern web design typically avoids dedicated printer-friendly pages by using CSS for print styles, and secure websites rarely use session IDs in URLs, but these legacy issues still exist.

Implementing Canonical Tags: HTML, HTTP Headers, and Sitemaps

You have multiple ways to implement canonical tags, depending on your content type and server configuration.

This is the most common and straightforward method for HTML documents. You place the <link rel="canonical" href="[absolute URL]" /> tag within the <head> section of the HTML page. Ensure it's present on every page, pointing to its preferred version. This method is easy to implement for web pages and is widely supported by search engines. The Mozilla Developer Network (MDN) provides comprehensive documentation on the rel="canonical" link type.

Canonical HTTP Headers for Non-HTML Documents

For non-HTML documents, such as PDFs or other file types that search engines might index, you cannot place an HTML tag. In these cases, you can use the HTTP Link header to specify the canonical URL. This is a server-side directive. The format looks like this:

Link: <https://www.example.com/documents/whitepaper.pdf>; rel="canonical"

You configure your web server (Apache, Nginx, etc.) to send this header with the response for the non-HTML file. The World Wide Web Consortium (W3C) provides information on this method.

Indicating Canonicals in XML Sitemaps

While not a primary method for establishing canonicals, your XML sitemap should only list the canonical versions of your URLs. If a URL is included in your sitemap, you are implicitly telling search engines that this URL is the preferred version for indexing. Including non-canonical URLs in your sitemap sends conflicting signals and can waste crawl budget. Always ensure your sitemaps are clean and contain only canonical, indexable pages.

"We recommend that you only list canonical URLs in your sitemaps. If you list non-canonical URLs in your sitemaps, Google Search may ignore them."

— Google Search Central, Consolidate duplicate URLs

Therefore, your sitemap acts as a strong hint reinforcing your canonical choices.

Canonical Tags vs. 301 Redirects: Knowing When to Use Each

Understanding the distinction between canonical tags and 301 redirects is critical for effective SEO. Misusing them can harm your site's visibility.

Feature rel="canonical" Tag 301 Redirect
Purpose Suggests preferred URL to search engines for indexing and ranking. Consolidates link equity without altering user experience. Permanently moves a page to a new URL. Automatically forwards users and search engines to the new location.
User Experience Users can still access and view the non-canonical URL. No physical redirection occurs. Users are immediately redirected to the new URL. The old URL becomes inaccessible directly.
SEO Signal Strength Considered a "hint" to search engines. May be ignored if conflicting signals are present. Considered a "strong signal" or "directive." Search engines almost always follow 301s.
Link Equity Transfer Passes approximately 99% of link equity to the canonical URL. Passes approximately 99-100% of link equity to the new URL.
When to Use Duplicate content that you want to keep accessible (e.g., product variations, faceted navigation, syndicated content, HTTP vs. HTTPS, www vs. non-www versions you cannot redirect). Page has permanently moved, URL structure changed, merging pages, removing deprecated content, site migrations.

The choice depends on whether you want to maintain the accessibility of the duplicate page while providing a strong SEO signal (canonical tag) or completely retire the old URL and direct all traffic and link equity to a new one (301 redirect). A site migration, for instance, typically involves thousands of 301 redirects, not canonical tags, to preserve SEO value from old URLs to new ones.

Google's Stance: Canonical Tags Are Hints, Not Directives

It is crucial to remember that Google, like other major search engines, treats the rel="canonical" tag as a hint, not a directive. While Google generally respects your canonical choices, it reserves the right to select a different canonical URL if it believes another URL is a better choice. This can happen due to various factors, including:

  • Conflicting Signals: Your internal linking structure, sitemap, or inbound links might point to a different URL than your canonical tag.
  • Content Similarity: Google's algorithms might identify another URL with more unique or authoritative content, or a page that receives significantly more external links.
  • Technical Errors: Broken canonical chains, canonicals pointing to 404 pages, or canonicals to noindexed pages can cause Google to disregard your hint.

Google's goal is to provide the best search results to its users. If your canonicalization doesn't align with what Google perceives as the most relevant and authoritative version of a page, it may override your suggestion. This highlights the importance of consistency across all your SEO signals and regular monitoring through Google Search Console to see what canonical URL Google has chosen.

You can find Google's official documentation on consolidating duplicate URLs at Google Search Central.

Hand holding magnifying glass over flowing data, graph rising
Regularly auditing your canonical tags ensures ongoing SEO health and performance.

How Proper Canonicalization Fuels Your Content Strategy with CitedGiraffe

Proper canonicalization forms the bedrock of an effective content strategy. Without it, even the most expertly crafted and optimized content can struggle to achieve its full potential in search rankings. CitedGiraffe's mission is to help you plan, write, and publish SEO and AI-optimized content on autopilot, but this assumes a technically sound foundation for your website. If search engines are confused about which version of your content to index, your ranking signals are diluted. Your high-quality content may not receive the visibility it deserves.

Imagine you use CitedGiraffe's AI tools to generate insightful, keyword-rich articles that perfectly match user intent. If your site has duplicate content issues, search engines might:

  • Waste Crawl Budget: Crawlers spend time processing duplicate pages instead of discovering your new, valuable content.
  • Dilute Authority: Link equity and ranking signals are split across multiple URLs instead of consolidating on your preferred page.
  • Misinterpret Intent: Search engines might index a less optimized version of your content, leading to lower rankings for your target keywords.

By implementing these seven canonical tag rules, you ensure that search engines always find and index the intended version of your content. This allows CitedGiraffe's AI and SEO optimization to operate on a clean slate, maximizing the impact of every piece of content you produce. When your technical SEO is robust, your content efforts yield better results.

CitedGiraffe helps you focus on creating exceptional content by handling the automation. You need to ensure the technical aspects, like canonicalization, are in order. This synergy ensures your content ranks higher, drives more organic traffic, and ultimately achieves your business goals. For guidance on selecting the right tools, consider exploring your ultimate guide to choosing an SEO content automation vendor.

Ensure Your Content Gets Found and Ranked

Effective content strategy relies on a strong technical foundation. Canonical tags are a critical part of that foundation. By mastering the seven rules outlined, you clarify your website's structure for search engines, prevent duplicate content penalties, and consolidate your link equity. This technical hygiene directly impacts your ability to rank for target keywords and drive organic traffic.

CitedGiraffe empowers you to create and manage high-performing content at scale. Our platform works best when your website's technical SEO is in top shape, ensuring your content is indexed correctly and receives the visibility it deserves. Start by scanning your site to identify any canonical issues or other technical SEO challenges. Then, let CitedGiraffe help you plan, write, and publish the content that truly moves the needle for your business.

Take the first step towards a technically sound and content-rich website today. Scan your site for free with CitedGiraffe and start optimizing your content workflow.

Next Steps

Implement and monitor your canonical tags to ensure your content is indexed correctly.

Days 1 to 30

  • Audit Existing Canonicals: Use Google Search Console and an SEO crawler (like Screaming Frog) to audit all existing canonical tags on your website. Identify any missing, incorrect, or conflicting canonicals.
  • Implement Self-Referencing Canonicals: Ensure every page on your site has a self-referencing canonical tag that uses an absolute URL.
  • Address HTTP/HTTPS and www/non-www: Resolve any inconsistencies by either 301 redirecting or canonicalizing to your preferred URL version.
  • Educate Your Team: Ensure anyone creating or publishing content understands the importance and proper implementation of canonical tags.

Days 31 to 60

  • Review Google Search Console: Check the "Pages" or "Index Coverage" report for "Duplicate, Google chose different canonical than user" warnings. Investigate and correct these issues.
  • Focus on E-commerce/Dynamic Pages: Prioritize pages with variants, pagination, or filtered navigation. Ensure their canonicals point to the correct, preferred versions.
  • Integrate with Content Workflow: Make canonical tag verification a standard step in your content publishing process. Ensure new pages or republished content adhere to canonical best practices.

Days 61 to 90

  • Monitor Ranking Trends: Observe if fixing canonical issues has led to improved rankings or reduced duplicate content warnings in Search Console.
  • Perform a Second Full Audit: Conduct another comprehensive audit to catch any new issues or missed items from the first pass.
  • Plan for Future Changes: Anticipate how site redesigns, migrations, or new content types might impact canonicals and integrate canonical planning into these projects.

FAQ

What is the primary purpose of a canonical tag?

The primary purpose of a canonical tag is to inform search engines which version of a web page is the preferred or "canonical" one when multiple URLs exist with identical or very similar content. This helps prevent duplicate content issues, consolidates link equity, and ensures search engines index and rank the most authoritative version of your content, ultimately protecting and improving your site's SEO performance.

Can a canonical tag point to a different domain?

Yes, a canonical tag can point to a URL on a different domain. This is particularly useful for content syndication, where your original content is published on other websites. By having the syndicated versions canonicalize back to your original article's URL on your domain, you ensure that your site receives the primary SEO credit and link equity, maintaining your authority as the original publisher.

What happens if I have conflicting canonical signals?

If you have conflicting canonical signals (e.g., your canonical tag points to URL A, but your internal links or sitemap point to URL B, or URL A is noindexed), search engines may become confused. They might ignore your canonical tag entirely and choose a different URL as the canonical version, or they might fail to index any version effectively. This can lead to diluted ranking signals, wasted crawl budget, and a negative impact on your search visibility.

Should every page on my site have a canonical tag?

Yes, as a best practice, every page on your site should have a self-referencing canonical tag. This means the canonical tag on a page points to its own preferred URL. Even if a page has no obvious duplicates, a self-referencing canonical proactively guards against minor URL variations (like tracking parameters) creating duplicate content issues and explicitly states your preferred version to search engines.

Sources