What Is Hreflang and What Does It Do? with Gary Illyes

In our second Virtual Keynote with Google Webmaster Trends Analyst Gary Illyes, Eric Enge asked him about how Google treats various SEO tags. In this post I will summarize what Gary had to say about the hreflang tag.
You can watch the segment where this discussion occurs here:

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What is the hreflang tag?

The hreflang tag is used when a site has various language versions of its pages. Hreflang tells search engines where to find those various versions so the engine can serve up the correct language version to each user.
Related: Learn how to implement hreflang on your site.

How does Google use hreflang?

The hreflang tag actually serves as a ranking signal of sorts. If Google sees the user is in France, or the query is in French (or if their interface is in French), then Google will rank the French version of the site indicated by the site’s hreflang tag first for that user.
An important parameter: in an hreflang tag you can specify language only, or language and country, but you cannot specify country only.
Also, hreflang tagging needs to be 100% reciprocal or Google will ignore those links from the cluster. So if the English page links to the French page, but the French page does not link back, then the French page will not get into the English page’s link cluster. Eric Enge noted that this is the most common mistake we see by sites that have multiple language versions.
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What if you have a lot of language variations? Wouldn’t that be a lot of code to put on each page? Gary said there is a limit to the number of hreflang links that Google will process on a page, but the limit is up in the hundreds. If heavy code in the header is a concern for a site, a workaround is to specify the hreflang links in the sitemap, eliminating that load from each page’s html (which could slow the load time of the page).