Percent-encoding

Percent-encoding is a mechanism to encode 8-bit characters that have specific meaning in the context of URLs. 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.