How does URL encoding work in web technologies?

URL encoding, also known as percent encoding, is a method to encode information in a Uniform Resource Locator (URL).

URL encoding is a crucial aspect of web technologies, particularly when it comes to transmitting data over the internet. It is a mechanism that converts characters into a format that can be transmitted over the internet. URLs can only be sent over the internet using the ASCII character set. Since URLs often contain characters outside the ASCII set, URL encoding replaces these unsafe ASCII characters with a "%" followed by two hexadecimal digits that represent the ASCII code of the character.

For instance, the space character is unsafe because it can be interpreted as a separator in URLs, so it is replaced with "%20". Similarly, characters like "<", ">", "#", "%", "{", "}", "|", "\", "^", "~", "[", "]", and "`" are also unsafe because they are used in defining the syntax of URLs.

URL encoding is used within the query string or the path component of a URL. In the query string, certain characters have special meanings and are reserved for special use. These characters include the question mark (?), ampersand (&), equals sign (=), and plus sign (+). If these characters are not used for their reserved purposes, they must be URL-encoded.

For example, if you wanted to include the ampersand character (&) in the value of a query string parameter (rather than to separate different parameters), you would need to URL-encode it. The URL-encoded version of "&" is "%26".

URL encoding is also used to encode binary data, for example in a GET request. Binary data is converted to a safe ASCII format using base64 encoding, and then any resulting unsafe ASCII characters are URL-encoded.

In summary, URL encoding is a fundamental part of how data is sent over the internet. It ensures that all data can be correctly and safely transmitted in a URL, regardless of the characters it contains.