x-default hreflang attribute value

[BeckyKey]

Hi

When is it best to use the  x-default hreflang attribute value tags?

Screaming frog is flagging lots as missing, but is it necessary?

Thanks

[zeehj]

Hey Becky–here's a primer on the hreflang tag that I recommend reading: https://moz.com/learn/seo/hreflang-tag

Essentially, if you have an international website with localized or translated versions (mexico.website.com, or website.com.mx, or website.com/mexico), you need to use rel="alternate" hreflang="es-mx" (using my Mexico example above) in the head tags of your site's pages.