Percent-encoding, also known as URL encoding, is a method to encode arbitrary data in a uniform resource identifier (URI) using only the US-ASCII characters legal within a URI. Percent-encoding is used to ensure special characters do not interfere with the URI's structure and interpretation. Special characters are replaced with a percent sign (%) followed by two hexadecimal digits representing the character's byte value. For example, a space is commonly encoded as %20:original: http://example.com/my file.txt encoded: http://example.com/my%20file.txt