Refers to a security system which protects your computer from un-authorised access through a network such as the Internet.

Firewalls are a vital piece of security for any computer connecting to an open network, especially the Internet.

Firewall systems can be either software based, like what you may have installed on your computer, or firmware based, where the firewall system is stored in ROM chips on a network device sitting between the local network and the open network.

Most firewalls can be extensively configured to allow different levels of security. Some common configuration options include:

Allow or disallow certain applications to connect to the network.
Allow or disallow the transfer of certain types of data.
Block or allow data being sent/received by certain ports.

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