hreflang tags or attributes are used to communicate to search engines the language used within a content page and to showcase variations of content based on users' locations.
What is the hreflang tag?
The hreflang tag, also referred to as hreflang attribute, is used to communicate to search engines which language a website uses on specific pages. This helps crawlers and search engines index the content properly and display it as a result in the search engine page results for people searching in that language.
To easily add (or identify) a hreflang tag in a page, use rel="alternate" hreflang="x". Here's a code sample for 2 variations of English on the same site:
<link rel="alternate" href="https://yourwebsite.com" hreflang="en-us" />
<link rel="alternate" href="https://yourwebsite.com" hreflang="en-uk" />
Why use hreflang tags on a website?
The main reason to use a hreflang attribute on the site is for localization purposes and to inform search engines about the language used on specific pages. If a website has multiple languages for the same page, the hreflang tag to showcase the fact there is targeted content for multiple languages or even variants of a single language. This is an extremely helpful tag to have on a website with variations in terms of currency, culture, or shipping.