Language is evaluated on a per-page basis for SEO
Does an entire website need to be translated to rank well in an alternate language? John responded to a question about whether it would be ok to only translate some pages in a website rather than the entire site. He answered that language is looked at on a per-page basis, rather than evaluating whole parts of a website, so this approach would be fine. He recommended making sure that internal linking is in place to these translated pages so that they can be found.
It is not possible to specify which countries and regions content should rank in
There is no way to prevent Google indexing content in specific countries and regions, even if it’s not targeted to that audience. The example given was a user who wanted English pages to rank only in the US and the UK. If Google deems the content as relevant to users in other locations, there’s every chance it will be indexed there too (and nothing that webmasters can do to prevent this).
Try to Have the Fewest Internationalised Versions of a Site
Adding many internationalised versions of a website increases the complexity, so you’re better to have fewer versions if possible, especially if you have pages where you can rely on geo-targeting without hreflang. You can use Search Console and web analytics to see if people are landing on the wrong pages, and implement hreflang for those. For different language versions, hreflang can help Google to show the right version, but searches for long tail content are easily recognisable for which language version to show, so hreflang may not be necessary.
Hreflang May Not be Necessary For Translated Versions of Pages
Pages with different language content don’t necessarily need hreflang because the text is different so Google would treat them as unique pages and not as duplicates.
Google Tries to Detect User’s Language Preferences if Using Default Version of Chrome
Google is aware that sometimes users download the default version of Chrome in English rather than their preferred language, and will try to detect this and show the correct language versions of pages to help with localization.
Hreflang is Not Required For Untranslated Pages
As hreflang is handled on a per page basis, if you have different language versions of your site but not every page is translated, it isn’t a requirement to have hreflang set up for these pages. John recommends choosing the method that best suits individual websites, this could be either including the URL in the hreflang set or not including the URL.
Hreflang Can be Implemented on Small Groups of Pages
Hreflang doesn’t have to be implemented across an entire site. Sometimes it makes sense to implement hreflang on individual pages or sections where there are problems, or where it is especially important that the correct page is shown.
You Can Publish Different Language Variations of Content Without Using Subdomains or Subdirectories
Content in different language variations should be on different URLs, but it doesn’t necessarily need to be put on subdirectories or subdomains. For example, this could be achieved with different parameters.
Google Have a List Of ccTLDs That They Treat As Generic TLDs
To find out if your website is treated as a generic domain, John recommends accessing the international settings in GSC and seeing if you can set an international target.