Firewall is a network security system that monitors incoming and outgoing network traffic based on certain rules and regulations. It creates a barrier between an internal and an external source (mainly the internet). They are broadly categorized as network firewalls and host-based firewalls. This technology came into being with the beginning of the internet in the late 1980s.
A firewall basically works as a filter between the computer or network and the internet. It is used in numerous ways in to add security in a business. Large business firms have complex firewalls to protect their information. A firewall can protect the outside computers to have an access to the inside network. It also prevents insider trading done by the employees for their own advantage.