A Virtual Private Network has many tasks to accomplish. First of all, it should provide you with confidentiality, i.e. to provide you with privacy by encrypting your internet traffic over a public network. All the information you send or receive online should be protected and secured. And a good VPN provider should not store any logs of what you do. No third parties should have the access to your personal data. Also, a VPN should provide you with unlimited bandwidth, fast speeds and unlimited server switching. Moreover, the VPN service should be compatible with most of your devices, so it needs to be supported by different operating systems. In addition, it should offer you the stable and reliable performance of its remote servers. Of course VPN providers have many other goals to achieve.
VPNs use numerous tunneling protocols to offer its users helpful features including the ones mentioned above. Here are the basic protocols: OpenVPN, PPTP, L2TP/IPsec.