The term firewall is derived from an automobile division. The firewall exists in the zone between the car's engine and the passenger's cabin of an automobile, and is used to prevent any heat/combustion from the engine reaching the people in the passengers cabin; in other words, it's a protective barrier. But in a network world, it is being used as a metaphorical term for how we separate our internal network from outside danger. Firewalls can be defined as any hardware or software that enables the filtering of the packets or controls the flow of traffic. They are generally implemented in a network perimeter. They act as a border for trusted and untrusted zones:
For a company, securing the network and data adds complexity. The costs of maintaining and implementing such high-level security for securing things such as e-commerce, intranet...