Encoding URLs

URLS must be sent over the Internet using ASCII characters. When a URL contains a character unavailable in the ASCII character set, the URL must be converted into valid ASCII characters. URL encoding, also commonly called percent encoding, replaces non-ASCII characters with a "%" and two subsequent hexadecimal digits. For example, a valid URL cannot contain spaces, which means the space character must be replaced. Space characters are often replaced with "%20" although sometimes you may see them replaced by a "+". For a full list of ASCII characters and their encoded replacement, see URL Encoding Reference.

Decoding URLS

Developers often find themselves needing to encode URLs to use them, particularly when configuring URLs for a web application or transferring data via HTTP requests. An encoded URL is often more difficult to read without first decoding the URL. For this reason a URL decoder utility is often used to view a more human-friendly format.