Uniform Resource Locator (URL)

Techopedia explains Uniform Resource Locator (URL)

Tim Berners-Lee and the Internet Engineering Task Force working group is credited with developing the URL in 1994. It is formally specified in RFC 1738.

All URLs are presented in the following order:

• Scheme name
• Colon and two slashes
• Location of the server
• The port (optional) and the location of the resource on the server
• Fragment identifier (optional)

So, the format will look like this:
scheme://location:port/file-on-server.htm?querystring=1

This looks more complex that it is. The most common schemes (protocols) are HTTP and HTTPS, which any WWW user will recognize. The location of the server is generally a domain name. Given this, the following URLs are much more simple to understand:

http://www.google.com/default.htm
https://www.google.com/default.htm

Both these URLs indicate that there is a file named default.htm on a server with the address of "google.com". One uses regular HTTP, while the other uses a secure version of this scheme.

Two common elements of confusion about URLs:

• The "www" is not actually part of the technical protocol. Websites just started using this to indicate the user is using the World Wide Web. This is why if you go to http://google.com, it redirects to http://www.google.com.
• Most users access the Internet via a Web browser, which inserts port 80 on HTTP connections behind the scenes. This is why if you go to http://www.google.com:80, you will see the same website as if there were no port number.

Finally, the following URL demonstrates a fragment identifier, more commonly known as a querystring:

http://www.google.com/some-page?search=hello

This is saying that to use the HTTP protocol to send a request to the website at google.com (over port 80) and to ask for "some-page" and send in the search variable "hello". This is why you'll sometimes see an extremely long URL as many variables are being sent to the Web server in more interactive Web applications.