The backslash is used for web URLs because it is the standard path separator in Microsoft Windows, the most widely used operating system for client computers. The forward slash is used for local directories in Unix-based operating systems because it is the standard path separator in Unix.

The backslash ( \ ) is a typographic and/or keyboard mark that is used in some programming languages and other computing contexts. In Windows systems, for example, the backslash is used to separate elements of a file path, for example: C:\Documents\User\File.

A trailing slash is a forward slash (“/”) placed at the end of a URL such as domain.com/ or domain.com/page/. The trailing slash is generally used to distinguish a directory which has the trailing slash from a file that does not have the trailing slash. However, these are guidelines and not requirements.

A slash, according to the Cambridge Dictionary, is defined as “the symbol / used in writing to separate letters, numbers, or words” and according to the Merriam-Webster Dictionary, “a mark / used typically to denote “or” (as in and/or), “and or” (as in straggler/deserter), or “per” (as in feet/second)”.