The purpose of using firewalls in enterprise networks is to establish a security barrier between the internal network and external threats such as unauthorized users and cybercriminals. Firewalls monitor and control incoming and outgoing network traffic based on predetermined security rules, helping to protect sensitive information and maintain data integrity. They can be hardware-based or software-based and play a key role in safeguarding networks from a variety of threats, including malware, intrusions, and data breaches, thus ensuring a secure operating environment.