What is a firewall
For example in an office set up it can stop employees looking at inappropriate sites and stop external criminals accessing company data.
In home networks, a firewall typically takes one of two forms:
Most will also provide control what services (ports) the protected computers are able to access on the Internet (outbound access).
Most firewall's intended for home use come with pre-configured security policies from which the user chooses, and some allow the user to customize these policies for their specific needs.