The hreflang tag specifies the language and geographical targeting of a webpage. It helps search engines like Google serve the correct version of a page to users based on their location and language preference. The tag is useful for brands doing global SEO that have content in multiple languages and regions. It can be implemented by adding a link element to the HTML head specifying the language targeting, or by submitting language version information to an XML sitemap. Examples are given of implementing hreflang tags via HTML and XML sitemap.