A firewall is a network security device positioned between two different networks, usually a company’s internal network and the Internet. A firewall ensures that all communications attempting to cross from one network to the other meet a company’s security policy. Firewalls track and control communications, deciding whether to allow, reject or encrypt communications. In addition to protecting networks from the Internet, firewalls are increasingly being deployed to protect sensitive portions of local area networks and individual PCs. When you connect to the Internet you are putting your data and your resources at risk, a firewall restricts people entering at a carefully controlled point and also prevents attackers from getting to close to your other defences.