In construction, a firewall is a non-flammable wall that prevents fires from spreading throughout a building. Homes, for example, may have a firewall between the garage and the rest of the house to prevent garage fires from threatening other rooms.
With the rapid popularization of the internet, the term firewall is more commonly used in computer networking. Like the firewalls used in homes and buildings, computer firewalls act as a barrier between computers on a network. For companies with a computer network or for individuals with a permanent connection to the internet (such as through DSL or cable), a firewall is critical. Without a firewall, intruders on the network would likely be able to destroy, tamper with or gain access to the files on your computer.
Firewalls can come in the form of hardware or software. Without getting into the complex details of how firewalls work, suffice it to say that function with a set of filters that are constantly monitoring traffic on the network. Whenever a packet of information triggers one of the filters, the firewall prevents it from passing through in the attempt to prevent damage. Of course, firewalls sometimes block wanted traffic, and through a continual process of refinement, the filters can be customized to improve their efficacy.
Many computer users who access the internet via a broadband router, may already be benefitting from a firewall. The router itself may be configured to serve as a firewall; any nefarious attacks from the network, are halted at the router thereby sparing any ill effects to the computer. Such a hardware firewall can be further bolstered with a secondary line of defense in the form of a software firewall; you can never be too safe when using the internet!
If you would like more detailed information regarding firewalls, how they work or how to configure them, etc. please visit the link provided in the source section below.