Understanding URLs

What is the protocol?

When referencing a web page, the protocol is allways "http://", which stands for Hypertext Transfer Protocol. There are other protocols which you might bump into from time to time, including:

• mailto:
• ftp://
• gopher://

What is the host?

The host is the name of the machine running the web server. Large companies or Universities quite often have more than one web server, and this is how you tell which machine is serving up these particular web pages. If there is only one web server, the host name is optional.

Is a URL case sensitive?

The part of the URL after the intitial slash (in pink above) is usually case sensitive (if the web server the web page is hosted on is running Unix operating system). If the web server is a Mac or PC then case doesn't matter.

I recommend naming all files and directories with lower case (otherwise people will quite often write them down incorrectly and are then unable to get back to your page.

What is the default file name?

Please note that if no filename is specified, as in all addresses above, that means that the web server will display whatever the default file is for that system, if one has been published in that directory. If no file with a default name has been published, then a list of all the files in that directory will display. On some systems the default file name is index.html or index.htm, on other systems that default file name might be default.html or home.html. Each server can be setup differently.