Iptables is a user-space utility program that allows a system administrator to configure the Linux kernel's packet filtering rules. It acts as a firewall, controlling the incoming and outgoing network traffic based on predefined rules. This helps protect systems from unauthorized access and various types of network attacks. The rules in Iptables are organized into different chains, such as INPUT, OUTPUT, and FORWARD, which correspond to different types of network traffic. Administrators can specify actions for packets that match certain criteria, such as allowing, blocking, or logging them, providing a flexible way to manage network security.