What is a Firewall? Well lets say your computer is your house. When the door is all the time open everyone can go in out as they want. A firewall is like a door with lock on. So you can lock people out from your computer if you think they shouldn't have access to it. So all the time someone wants to get in they must knock on the door and you decide if you want to let them in or not. So what happened when you don't have a firewall? well your computer will definitely have a lot of unwanted guests on your system. Firewall also can block attacks attempts on your computer like "Denial Of Services" attacks. There goal is to flowed your computer with packets. When you have a Firewall on the computer the packets wont reach the computer since it only hit the door so wont open up :p So now you know what a Firewall is lets take a look on AV.. What is a Anti-Virus? Sometimes you are downloading things you think is safe to use. But it isn't thats why you need a Anti-Virus Program. so can take away the unwanted program you gave access to your system since they doesn't want to go without a battle. They are designed to detect unwanted guests on your computer. So the Anti-Virus is basicelly a Guard so are watching if everything is ok. Why shouldn't i run two AV's at the same time? Well when you first hear this you may think well this must definitely give higher Protection. This may freeze and crash the computer. Why this happens is when both AV's are watching the same file. This can also Slowdown the system Performance. Why should i download a Firewall when i already have Windows Firewall? When i have used Windows Firewall. I feel its never communicate with me at all. It doesn't ask about anything. Also another thing why you should get a other Firewall is since the Windows Firewall can only trace Incoming traffic and not outgoing. Also there is a lot of other tools you can use but this is the main security tools everyone must have.