A virtual private network is the process of creating a private network that can then connect to the public network. A VPN achieves this by first creating a VPN tunnel and then sends the data in that channel with the same encryption. Thus, one cannot intepritate the data sent inside the channel.
VPN achieves this by using some famous protocols:
PPTP: Point to Point Tunneling Protocol is a type of protocol that was intially introduced by Microsoft, PPTP encrypts the data but with years, it has become obselete and is rarely ever used.
L2TP: Layer 2 Tunneling Protocol is an upgraded version of PPTP. L2TP uses IPSec encryption where the information is encapsulated and thus making it slightly hard to interpritate. There are reports by Edward Snowden that this protocol was broken by NSA.
SSTP: Secure Socket Tunneling Protocol is another type of protocol which was introduced by Microsoft. SSTP uses SSL 3.0 encryption methods. Although SSTP is available for Linux and other operating system, it is most commonly used in Windows Operating System.
OpenVPN: The most commonly used VPN protocol. Famous VPN provides such as Nord VPN, Hotspot Shield, Express VPN and many more uses OpenVPN as their preferred default. Open VPN uses AES (Advanced Encyption Standards) and has many failproofs, thus making this the best protocol for the VPN. Since this is used by most VPN providers, this protocol is included in their VPN softwares by default.
1. VPNs are not always safe, VPNs can surely be traced depending on how series the outcome is using them.
2. Yes, they change your IP and yes, that means you can access differet libraries of Netflix and/or Amazon Prime.
3. Free VPNs can only be used if you really need to. Opera provides a free VPN service if you want to use VPN just to access libraries of different countires of your favorite streaming network. For other secure transactions, it is recommended to purchase a dedicated VPN service.