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The internet is a worldwide collection of computer networks. The term ‘internet’ refers to the network infrastructure, not the content stored on it.

The purpose of the internet is to enable communication on an international scale. Any device which connects to the internet - whether a PC, smartphone or internet fridge - becomes part of the internet, no matter where it is based.

The internet largely works on the client-server model. For example:

• web servers store and maintain web content, which is downloaded upon request to client computers
• mail servers handle web-based email
• media servers allow clients to stream music and videos

Hosting

Hosting is the storing of files and data on a web server. The web server is referred to as a host.

The URL (uniform resource locator) for a website includes the host name. For example, the host name bbc.co.uk is included in the URL www.bbc.co.uk.

The host name consists of three hierarchical levels, which work in reverse order of the name:

The top level root is generic to many websites. Examples of this level include:

• .com
• .uk
• .net
• .gov
• .edu

The second level denotes the type of organisation:

• .co
• .org
• .sch
• .ac

The third level is the organisation name:

• bbc
• ocr
• microsoft
• apple

Put together, unique domain names can be created.

Domain name servers (DNS)

Every website on the internet has a network address, consisting of four sets of three digits. For example, the ����ý website's address is 151.101.128.81.

Addresses like this are hard for users to remember. Instead, websites are accessed using domain names, for example, ‘bbc.co.uk’. Domain names are much easier for users to remember.

When a user visits a website, they enter the domain name as a URL. For example, the ����ý website’s address is www.bbc.co.uk. A domain name server takes the domain name and looks up its equivalent network address. The user’s request is then forwarded to the server that resides at that network address.