URL decoding is the process of converting URL-encoded strings back to their original form. URL encoding is a process of converting special characters in a URL into a form that can be transmitted over the internet without causing issues. The encoding is usually done by replacing the special characters with a percent sign followed by two hexadecimal digits that represent the ASCII code of the character.
For example, the space character " " is encoded as "%20", and the plus sign "+" is encoded as "%2B".
Note that some characters, such as letters and numbers, do not need to be encoded in a URL. However, it's important to encode all special characters to ensure proper transmission of the URL over the internet.