IPSec (Internet Protocol Security) is a suite of protocols designed to secure Internet Protocol (IP) communications. It achieves this by authenticating and encrypting each IP packet in a communication session, ensuring that data remains confidential and tamper-proof during transmission over networks. IPSec operates in two modes: Transport Mode and Tunnel Mode. In Transport Mode, only the payload of the IP packet is encrypted, while the header remains intact. In Tunnel Mode, the entire IP packet is encapsulated within a new packet, providing an additional layer of security, making it ideal for Virtual Private Networks (VPNs) and secure site-to-site connections.