1. Background

Understanding the following isn’t essential, but it can be helpful.

The Internet

Inter-networking, the transfer of information between computerised devices, including the ‘core’ hardware of the internet, ‘mainframe’ computers, desk computers, tablets or mobile phones, whether connected by wires or wirelessly, is made possible by an underlying software mechanism known as Internet Protocol (IP). Each device on the internet is identified by an IP address. In IP version 4 (IPv4) this is given in the form of four hexadecimal numbers, such as:

or, in the later IP version 6 (IPv6) standard, as six digits, such as:


The latter, with the option of multiple colons in place of zero values, can also be given as:


The IP4 system can’t hold enough numbers to accommodate all the users in the world. For this reason any casual visitor to the internet, using software on a client device, is given any available address at the time of logging on: such an address is known as a dynamic IP address, since it can be different each time you log on. Other computers, such as a server that provides an always-on facility, are given a fixed or static IP address to ensure they can always be reached.

File Locations

The location of any file on the internet is given by its Uniform Resource Locator (URL), a form of addressing that can look something like this:


where xx.xx.xx.xx is the IP address of the computer holding the file.

The letters prior to :// indicate the protocol in use. In this case it’s Hypertext Transfer Protocol Secure (HTTPS), as used for a secure website on the World Wide Web, communication data being encrypted with Transport Layer Security (TLS) or the earlier Secure Sockets Layer (SSL).

Older insecure websites use an earlier protocol, known simply as Hypertext Transfer Protocol (HTTP), in which communication is via plain text, an unsafe way of working, and addressed as:


In the above URL, the IP address of the computer is followed string of characters. These show that the site’s home page, index.htm, is in a directory, otherwise known as a folder, called foldername. The / (forward slash) character, separates items in different directories.

The Domain Name System

Most websites don’t use a numerical IP address in their URLs. Instead, they employ the Domain Name System, which relies on special computers, known as name servers to act as lookup directories, converting a web address entered by a user in this form:


into this underlying URL:


where xx.xx.xx.xx is the IP address, allowing a site to be located without the user ever knowing about the underlying workings.

Domain Names

A typical website domain name looks something like this:




in which each part of the name is divided by full-stops into domains. In this instance we have nameofmysite, co and uk domains. The Top Level Domain (TLD) is the text to the extreme right, and is chosen to match the type of business, organisation or a country code, although the latter isn’t obligatory for websites aiming at an international audience. Where a country code is given there’s always a second domain to the left of it, appropriate to the activities of the site.

Some websites employ one or more subdomains, located to the left of the main name, as in:


Such a subdomain operates as an entirely separate site, adding another level of complication. The www subdomain, however, is commonly used, especially in older sites, as in:


Web Browser Operation

Websites are normally viewed by means of an application known as web browser. When you enter the name of a site into a browser’s address bar, and press the return key, the application goes to the nearest name server, which then directs it to the site’s IP address. It then checks to see if HTTPS or HTTP protocol is being used at the location and looks for a home page file with the name index.htm or index.html. So, if you enter:


you should end up with a URL looking something like this in the address bar:


Entering www.nameofmysite.com or nameofmysite.com into your browser’s address bar usually gives the same result, with the browser actually going to either one of the addresses. However, this only happens when the administrator of a site owns both the parent and the www subdomain, which is the usual arrangement. There may be some instances, however, where the site with a www subdomain is actually an entirely unrelated site to the one without.