A VPN (Virtual Private Network) is a technology that allows creating a secure and protected connection between two devices on a public network, such as the internet. By using a VPN, the exchanged information between devices is encrypted, making it difficult for hackers or other malicious individuals to intercept and decrypt the data.

In practice, when using a VPN, internet traffic is routed through a remote VPN server, which acts as an intermediary between the user's device and the rest of the network. This makes it difficult for intruders to access the user's private information, such as passwords or sensitive data.

Additionally, a VPN can also allow users to mask their geographical location, making it possible to access online content that might be blocked based on location.

In summary, a VPN is a tool used to ensure the security and privacy of communications on the internet, making it difficult for intruders to access users' confidential information and allowing them to browse anonymously.

Using a VPN can protect against sniffing on public networks by encrypting internet traffic and making it difficult for hackers to intercept and decrypt users' sensitive information.