URL

A URL such as https://shop.example.com/shoes?colour=red#reviews has several parts: the scheme (https), the host name (shop.example.com), the path (/shoes), a query string of key-value pairs (?colour=red) and an optional fragment (#reviews) that points to a spot on the page. A port number can follow the host, but browsers hide the defaults, 443 for HTTPS and 80 for HTTP.

Characters with a special meaning, such as spaces, question marks and ampersands, must be percent-encoded, so a space becomes %20. The fragment never reaches the server; it stays in the browser. Clean, stable, readable URLs help people and search engines alike, and changing them later needs redirects so that old links keep working.