Definition: An HTML attribute that tells search engines what language a page is intended for and which region it is intended for, for example, de-DE German in Germany, de-AT for German in Austria.
Everyday analogy: Like the language label on a book cover: “This edition is for readers in Austria; the German-Swiss edition is on the next shelf.”
How we use it: For multilingual sites, we check hreflang consistency during our SEO audit, incorrect or missing tags cause Google to display the wrong language version.