What does the phrase URL mean, and what does "case sensitive" mean in relation to web sites? - Killian O'Brien, Co Dublin.

It basically describes what a web address is: a Uniform Resource Locator.

Just as every page in a book or newspaper has a number, or very occasionally a letter, to allow for identification, every web page has a unique URL to allow access to it.

Each URL can further be broken down into three distinct constituent parts. These are known as: the protocol; the host name; and the file path. Examine the following URL for instance, http://www.theage.com.au/entertainment/specials.html

The http:// is the protocol. It tells us that this is a HyperText file on the World Wide Web. We do not need to see the www part to ascertain this. Many sites do not use www in their URL.

After that, everything up to the initial single slash refers to the host's name. In this case it is a newspaper called The Age. The fact that it is a .com.au address lets us know that it is based in Australia. The most common host name ending is .com, which is a US service. Many of the sites using .com are, however, not American. For instance, The Irish Times's web site is located at www.ireland.com. This is a subject to which we will return. Finally, the file path in the example here shows that "specials" is contained in a directory called entertainment.

The phrase "case sensitive" refers to the fact that you need to be careful to correctly type the case of a letter when writing in a web address. While some sites will automatically adjust capitals (A B C) to lower case (a b c), and direct you to the right place, there are many that do not have that facility, so you may end up being erroneously told that the site you are seeking does not exist.

Contact: Send your WebWorld queries to pcollins@ irishtimes.ie or by post to Padraig Collins, The Irish Times, D'Olier Street, Dublin 2.