A VPN creates an encrypted tunnel from your device to a VPN provider, then sends your internet traffic onward from the provider's network.

That changes who can see what.

What it helps hide from the local network / ISP

With a correctly configured VPN, your ISP or coffee-shop network can generally see that you are communicating with the VPN server and how much traffic is flowing, but not the ordinary destination IPs/domains of each tunneled connection in the same direct way.

HTTPS already encrypts the contents of most modern web traffic even without a VPN. A VPN adds a network-level tunnel around the connections and changes the public IP address seen by destination sites.

What it does not hide

A VPN does not stop a website from recognizing you through:

• logging in;
• first-party cookies/storage;
• tracking pixels;
• browser fingerprinting;
• account/payment identifiers;
• information you voluntarily provide.

It also does not make malicious downloads safe or magically protect a compromised device.

Big idea: A VPN does not remove trust; it moves some network visibility from your ISP/local network to the VPN provider.

That makes provider policy and incentives important. A dubious “free VPN” can be a worse privacy choice than a reputable paid service.