Most people use the term ‘URL’ interchangeably with ‘web address’, but in fact web addresses are just one type of URL. A URL can refer to any type of name or resource (files, programs, web pages) on the internet.
The term URL stands for Uniform Resource Locator, and is also sometimes written as URI (for Uniform Resource Identifier).
URLs were invented in 1994 by a group of internet pioneers including Tim Berners-Lee (the inventor of the World Wide Web) and Marc Andreesen (co-author of the first widely-used graphical browser, Mosaic). The aim was to make it possible to share information reliably by giving every file or page a consistent type of address.
What elements make up a URL?
URLs are made up of a number of elements that help point accurately at a specific piece of information.
Firstly, they have a protocol, such as ‘http’ followed by a colon and two forward slashes, that identifies the type of computer program that will be needed to display or process the information being located.
Secondly, there’s a name made up of numbers or words that identifies the computer or network hosting the information.
Thirdly, they have a port number which the sending and receiving computers use to establish a direct connection. This is often omitted, as the commonly-used services have agreed on standard port numbers - eg port 80 for web services.
Fourthly, there is a path made up of words that identifies the precise location of the information on the host computer or network.
And finally, there may also be a question mark followed by a string of words, letters, and/or numbers. You'll typically find these when you've entered a query into a search engine - the URL contains the information the computer needs to conduct the search and find your results.
‘Identifiers’ and their uses
Most people do not realise that their web browsers can handle many types of URLs that are not web addresses. Some samples of these identifiers and their uses include:
- HTTP - a web address.
- HTTPS - a secured web address which is used for encrypted connections such as those used for financial transactions.
- FTP - ‘File Transfer Protocol’, a more efficient (and older) way of transferring large files than HTTP.
- FILE - a file on the computer or local network the browser is running on.
- GOPHER - an older but still active type of server that indexes and searches content on the web.