An anti-virus and a firewall protect your computer in different ways.
- examines software and files as they are written on to or read from your computer's hard drive
- determines whether or not this software is malicious
- blocks malicious software (malware) from infecting your computer.
- filters network traffic to and from your computer or local network
- prevents hackers from accessing some parts of your computer or local network
- prevents some viruses from spreading over the network.