Tunnel mode is a method used in VPNs (Virtual Private Networks) to encapsulate and encrypt data packets. In this mode, the entire original packet, including its header, is wrapped inside a new packet with a new header. This process ensures that the data remains secure as it travels over the internet, protecting it from potential eavesdroppers. In tunnel mode, the original sender and receiver are not directly visible to each other. Instead, the data is sent through a secure tunnel created by the VPN server. This adds an extra layer of privacy, making it difficult for anyone to intercept or decipher the information being transmitted.