How to use canonical tag to improve your SEO?

Capgo

— 4 min read
How to use canonical tag to improve your SEO?

Based on my years of experience in SEO with CapGo AI: A canonical tag (also known as a rel="canonical" tag) is an HTML element that helps search engines understand which version of a page is the "official" or "preferred" version when there are multiple pages with similar or duplicate content.

What is a Canonical Tag?

A canonical tag is placed in the <head> section of an HTML page and tells search engines which URL should be considered the primary one when there are duplicate or near-duplicate pages. This helps prevent search engines from penalizing a site for duplicate content.

Example of a Canonical Tag in HTML:

htmlCopy code<head>
<link rel="canonical" href="https://www.example.com/preferred-page-url" />
</head>

In this example, the canonical tag tells search engines that the preferred version of the content is located at https://www.example.com/preferred-page-url.

Why are Canonical Tags Important?

  1. Duplicate Content Issues: If a website has multiple pages with very similar or identical content (for example, product pages with slight variations in color or size), search engines may struggle to determine which page to rank. This can lead to "duplicate content" issues where multiple pages with almost identical content compete against each other in search results, potentially lowering the site's overall SEO performance.
  2. Avoid SEO Penalties: Search engines like Google don’t necessarily penalize for duplicate content, but they do prioritize one page over the others. If you don't use a canonical tag to indicate which page should be ranked, Google may not index the page you prefer, or it may split ranking signals between the duplicate pages, resulting in lower visibility.
  3. Consolidate Link Equity: When multiple pages have similar content, they may receive backlinks (external links) from other websites. Without canonical tags, each of these pages may receive some of the link equity (SEO value), which can be diluted. By using canonical tags, you can consolidate link equity to the preferred page, improving its ranking potential.

When Should You Use a Canonical Tag?

Canonical tags are useful in several situations:

  1. Duplicate Content: When you have multiple pages with very similar content, such as:
    • Product variants (e.g., a t-shirt in different colors or sizes).
    • Printer-friendly versions of content.
    • Paginated content (like multiple pages of an article).
  2. Content Syndication: When you publish content on multiple websites (e.g., guest posts, syndication, or partner sites), a canonical tag can point to the original version of the content.
  3. URL Parameters: If your site uses URL parameters (like ?sort=asc or ?ref=ad), search engines may treat these as separate pages. A canonical tag can point to the "clean" version of the URL, helping prevent duplicate content issues.
  4. Faceted Navigation: E-commerce websites with faceted navigation (filters like price range, category, or color) can create many URLs with similar content. A canonical tag helps signal the primary version of the page to Google.

How Canonical Tags Work

  1. Search Engine Crawling: When a search engine crawls your site and encounters a canonical tag, it follows the link provided in the href attribute.
  2. Ranking: The search engine will consider the page specified in the canonical tag as the primary version, consolidating signals like ranking, backlinks, and content relevance to that page.
  3. No Indexing of Duplicates: Even if a page has duplicate content, the search engine will not index it as a separate result. Instead, it will index and rank the canonical version of the page.

Example of a Scenario Using Canonical Tags

Imagine an e-commerce store selling a blue shirt and a red shirt. Both pages have similar content, with only the product description and the image changing. Without a canonical tag, Google might treat the two pages as separate entities and split the SEO value between them, which could harm the rankings of both.

However, if you place a canonical tag on the red shirt page that points to the blue shirt page (or vice versa), Google will understand that both pages represent the same product, and it will consolidate the ranking signals to the canonical (preferred) page.

Example of a Canonical Tag in this Case:

  • Red shirt page: <link rel="canonical" href="https://www.example.com/blue-shirt" />
  • Blue shirt page: <link rel="canonical" href="https://www.example.com/blue-shirt" />

Common Mistakes with Canonical Tags

  1. Pointing to the Wrong URL: Always make sure the canonical tag points to the correct preferred version of the page. If you accidentally point to the wrong page, you could harm the SEO of your entire site.
  2. Not Using Canonical Tags Where Needed: Failing to use canonical tags on duplicate or near-duplicate pages may lead to confusion for search engines and lost ranking potential.
  3. Using Canonicals for Non-Duplicate Content: Don’t use canonical tags unless necessary. If pages have genuinely unique content, don’t use a canonical tag just to consolidate them. It may confuse search engines and harm your SEO.
  4. Self-Referencing Canonical Tags: On pages that are unique (not duplicates), it's a good practice to include a self-referencing canonical tag, i.e., a canonical tag that points to the same URL. This helps reinforce the signal to Google that the page is indeed unique.Example:htmlCopy code<link rel="canonical" href="https://www.example.com/unique-page-url" />

Best Practices for Canonical Tags

  1. Use HTTPS URLs: Always point to the HTTPS version of a URL if you have both HTTP and HTTPS versions of your site.
  2. Consistency: Make sure your canonical tags are consistent across all versions of the page (e.g., paginated pages, URL parameters).
  3. Avoid Canonical Chain: Ideally, there should be no “canonical chain” (i.e., page A points to page B, and page B points to page C). This could confuse search engines. Always point to the most authoritative version.
  4. Test and Monitor: Use tools like Google Search Console to monitor how Google is handling your canonical tags and ensure they are being implemented correctly.

Conclusion

In summary, canonical tags are a powerful tool in SEO that help prevent issues with duplicate content and consolidate ranking signals to a preferred page. By properly implementing canonical tags, websites can maintain SEO value, avoid penalties, and ensure their content is correctly indexed and ranked by search engines.

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