Internet security has become an important issue now-a-days. And it's like an evil which if left to spread will in no time have effects on the people all. This paper examines internet security with the use of firewall and how it can be used for internet security. A firewall is a part of a computer system or network which is designed to block unauthorized access to their system. This paper takes the descriptive method of writing. The techniques and types of firewalls are also discussed. This paper also discusses firewall and how it can be used to help in internet security.