URL encoding, also known as percent-encoding, is a mechanism for encoding special characters in Uniform Resource Locators (URLs) to ensure they are transmitted and interpreted correctly.

Some characters, such as spaces, slashes, and question marks, have special meanings in URLs and must be encoded to avoid confusion. URL encoding replaces these characters with a percent sign (%) followed by two hexadecimal digits.

For example, the space character is encoded as %20, the forward slash as %2F, and the question mark as %3F.