HTML Meta Tags

Two pages can look exactly the same in the browser window and still behave very differently. One shows its accented letters correctly, fits the screen of a phone, and appears in search results with a clear one-line summary. The other shows broken symbols, opens zoomed out on a phone, and appears in search results with a sentence that the search engine picked from the page. The difference is a few lines inside <head> that the reader never sees.

Information about a page, rather than the page content itself, is called metadata, which simply means "data about data