What a VPN changes
Without a VPN, your internet traffic normally travels from your device through the local router and your internet service provider before it reaches a website or application. HTTPS already encrypts the content of most modern web sessions, but network operators can still observe connection metadata such as the destination service, timing, volume, and the public address assigned to you. A VPN adds another encrypted tunnel from your device to the VPN provider. The destination then sees the VPN server’s public address instead of the address assigned by your home, mobile, hotel, school, or office network.
This change can be valuable on public Wi-Fi, while travelling, when a network is aggressively profiling connections, or when you want websites to receive a different network location signal. It does not make an account anonymous after you sign in. A website can still recognize you through login details, cookies, device characteristics, payment records, or information you deliberately submit. A VPN also moves part of the trust relationship from the local network and ISP to the VPN provider, so provider policy and engineering quality matter.