All of your internet traffic is sent through one of your VPN's servers, where it is encrypted. Your ISP can no longer see your internet activity, where you've come from, or track you because it's encrypted.

Your traffic is then forwarded to the website you're visiting by your server. Instead of your device, the site views the server as the source of your traffic. This means it sees your VPN server's IP address rather than your own.

The short answer is that it is secure, the ‘how secure part' is entirely determined by the supplier or service provider. Below are some of the security measures it provides: 

 

Tunneling

Tunneling is essentially a virtual tunnel through which your data goes so that neither your ISP nor anybody else can see it. Data packets are used to send and receive data from and to your machine. The request you are sending, the protocol, and the sender's IP address are all included in packets.

Encryption

To add an extra layer of protection and anonymity, VPNs encrypt the data packets you send to the distant server. Your data is encrypted locally, then sent across a tunnel to a remote server, where it is decrypted.

Virtual Private Network Protocols

Understanding VPN security requires knowledge of the most prevalent protocols used by VPNs, as well as the distinctions between them. While an automatic connection should keep you anonymous, some companies employ a more secure protocol.

VPN Log Handling

All of a Virtual Private Network provider's efforts would be for naught if your activities were still being logged. Simply put, you're transferring it from one organization to another. Good VPN companies take precautions to anonymize you on their remote servers and do not keep track of your incoming traffic.