Internet Protocol Security (IPsec) 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 unaltered during transmission. IPsec can be used in both IPv4 and IPv6 networks, making it versatile for various applications. 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, often used in Virtual Private Networks (VPNs).