A firewall is a device that protects a computer from some types of malicious network activity. Firewalls restrict certain types of network traffic; for example, blocking attempts to read files on your hard drive. Firewalls may also keep logs of network activity that might be useful if someone attempts to break into your computer. A firewall should be used to protect any computer connected directly to the Internet or any other public or untrusted network.
Use the following steps to open Windows Firewall.
Firewall Frequently Asked Questions