A firewall is like locking the front door to your house—it helps keep intruders (in this case, hackers and malicious software) from getting in. Windows Firewall is on by default in Windows 7, so you don't need to set it up—plus we've made it more flexible and easier to use.
Now you can fine-tune the protection and notifications you want for each of your network profiles—Home, Work, and Public. When you're connected to a public network like a library or a coffee shop, you may want to block all incoming connections. At home or work, this might be overkill. Whatever level of protection you choose for your profiles, you'll be able to switch between them with ease.
Windows Firewall can tailor protection for different network environments.