Thẻ canonical

What is a canonical tag?

A canonical tag (aka "rel canonical") is a way of telling tìm kiếm engines that a specific URL represents the master copy of a page. Using the canonical tag prevents problems caused by identical or "duplicate" nội dung appearing on multiple URLs. Practically speaking, the canonical tag tells search engines which version of a URL you want khổng lồ appear in search results.

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Code sample

The homepage has a self-referential canonical tag.

3. Spot-check your dynamic canonical tags

Sometimes bad code causes a site lớn write a different canonical tag for every version of the URL (completely missing the entire point of the canonical tag). Make sure lớn spot-kiểm tra your URLs, especially on e-commerce và CMS-driven sites.

4. Avoid mixed signals

Search engines may avoid a canonical tag or interpret it incorrectly if you send mixed signals. In other words, don’t canonicalize page A -–> page B và then page B -–> page A. Likewise, don’t canonicalize page A -–> page B & then 301 redirect page B -–> page A. It’s also generally not a good idea lớn chain canonical tags (A-–>B, B-–>C, C–->D), if you can avoid it. Sover clear signals, or you force tìm kiếm engines to lớn make bad choices.

5. Be careful canonicalizing near-duplicates

When most people think of canonicalization, they think of exact duplicates. It is possible to lớn use the canonical tag on near-duplicates (pages with very similar content), but proceed with caution. There’s a lot of debate on this topic, but It’s generally ok lớn use canonical tags for very similar pages, such as a product page that only differs by currency, location, or some small sản phẩm attribute. Keep in mind that the non-canonical versions of that page may not be eligible for ranking, và if the pages are too different, tìm kiếm engines may ignore the tag.

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6. Canonicalize cross-domain name duplicates

If you control both sites, you can use the canonical tag across domains. Let’s say you’re a publishing company that often publishes the same article across half a dozen sites. Using the canonical tag will focus your ranking power on just one site. Keep in mind that canonicalization will prevent the non-canonical sites from ranking, so make sure this use matches your business case.

Canonical tags vs. 301 redirects

One comtháng SEO question is whether canonical tags pass link equity (PageRank, Authority, etc.) like 301 redirects. In most cases, they seem to lớn, but this can be a dangerous question. Keep in mind that these two solutions create two very different results for search crawlers & site visitors.

If you 301 redirect Page A-->Page B, then human visitors will be taken khổng lồ Page B automatically và never see Page A. If you rel-canonical Page A-->Page B, then search engines will know that Page B is canonical, but people will be able khổng lồ visit both URLs. Make sure your solution matches the desired outcome.

How to Audit Your Canonical Tags for SEO

When auditing your canonical tags, there are a number of things worth checking for optimal SEO performance. Here"s a checklist:

Does the page have a canonical tag?Does the canonical point lớn the right page?Are the pages crawlable và indexable?

A common mistake is to point the canonical at a URL that is either blocked by robots.txt, or is set to "noindex". This can skết thúc mixed và confusing signals to search engines. A few common ways to lớn inspect & audit your canonical tags are below.

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1. View-source

In most browsers, you can right-cliông chồng to view-source, or simply type it inlớn the address bar, lượt thích this:view-source: the source code, tìm kiếm for canonical tag in the . If present, it should look lượt thích this:


3. phân tích và đo lường in Bulk with Software Solutions

Most SEO site audit software allows you lớn audit canonical tags in bulk. Pro checks for missing canonical tags, and can bởi so for 100s of thousand of pages at a time.


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