In a normal way Firewall means a wall or partition designed to inhibit or prevent the spread of fire. In computing way firewall is a wall and shield that protect a network or system from unauthorized access via outer.
Firewall is a security system which protects the System from Intruders and hackers. It is a network security device that keeps an eye on incoming and outgoing traffic and stop and slowdown viruses and malware to spread from one computer or sub net or network to another.
Firewall uses a define set of rules and terms for checking and filtering packet. Firewall security device filter outgoing and incoming traffic and only allows that traffic which fulfill all rules. Firewall decides whether to allow or block specific traffic according to security rules.
Example-You could think of a firewall as a security guard that decides who enters or exits a building.
Example- You could also think of a firewall as airport security. Only authorized person can go to take a flight. A person can go inside only when he/she pass all security checks
Firewall can divide into two categories- A firewall is a software utility or hardware device that acts as a filter for data entering or leaving a network or computer.
Hardware: Basically the router is used for hardware firewalls but any other security product can also use. Hardware firewall is placed between your PC and the outside world. Router and Security device can connect more than one device at a time. It is a tangible product or devices that secure system and PC from outer threads, viruses, malware and many more harmful viruses.
Software Firewall: Software firewall is an intangible product. Software Firewall is a program and set of codes that install in computer or system. In case of attack software firewall hide open ports and will deflect incoming attacks. Software Firewall also aware and warn from suspicious outgoing traffic. When software firewall present in a system an attacker will have to cross two level securities to access your PC and it’s too difficult for any attacker.
Firewall support services are like a back bone for every system and network. Firewall can secures and protects network of both sides, client sides and server sides and deliver only useful content.