Firewall is a network security device, either hardware or software based, which monitors all incoming and outgoing traffic and based on defined set of security rules it accept, reject or drop that specific traffic. A Firewall is a type of cybersecurity tool that is used to filter traffic on a network. Firewalls can be used to separate network nodes from external traffic sources, internal traffic sources, or even specific applications. The primary goal of a firewall is to block malicious traffic requests and data packets while allowing legitimate traffic through.
The Internet is really one large network, which includes your computer. A firewall protects your computer by acting as a gate through which both all data must pass. By blocking certain kinds of traffic, the firewall protects your computer or network from unauthorized users and safeguards your data from attack.