Percent-encoding is a mechanism to encode 8-bit characters that have specific meaning in the context ofURLs. It is sometimes called URL encoding. The encoding consists of a substitution: A '%' followed by the hexadecimal representation of the ASCII value of the replaced character.

Special characters needing encoding are:':','/','?','#','[',']','@','!','$','&',"'",'(',')','*','+',',',';','=', as well as'%' itself. Other characters don't need to be encoded, though they could.

Depending on the context, the character' ' is translated to a'+' (like in the percent-encoding version used in anapplication/x-www-form-urlencoded message), or in'%20' like on URLs.

See also

• Definition ofpercent-encoding in Wikipedia.
• RFC 3986, section 2.1, where this encoding is defined.
• encodeURI() andencodeURIComponent() — functions to percent-encode URLs