A URL is an address for a website. Just like postal addresses have to follow a specific format to be understood by the postman, URLS have to follow a format to be understood and get you to the right location.
There are only certain characters that are allowed in the URL string, alphabetic characters, numerals, and a few characters `; , / ? : @ & = + $ - _ . ! ~ * ' ( ) #` that can have special meanings.
#### Reserved Characters:
| Character | Meaning |
| --- | --- |
| : | Separate protocol (http) from address |
| / | Separate domain and directories |
| # | Separate anchors |
| ? | Separate query string |
| & | Separate query elements |
| @ | Separate username and password from domain |
| % | Indicates an encoded character |
| + | Indicates a space |
#### Encoding:
Any character that is not an alphabetic character, a number, or a reserved character being used needs to be encoded.
URLs use the ASCII ("American Standard Code for Information Interchange") character-set and so encoding must be to a valid ASCII format.
There are functions in most web languages to do this encoding for you, for example in JavaScript `encodeURI()` and in PHP `rawurlencode()`.
