What is a VPN?

A virtual private network (VPN) protects your data and identity over public networks, like the Internet and wireless hotspots. Various protocols are used to create an encrypted tunnel that transports data securely. While a firewall may protect the data on your computer, a VPN will protect your data on the Internet. The goal of a VPN is to implement the same level of security provided by private networks at substantially lower costs.

Why use a VPN?

Most VPN's are used to add security. Today's world is evolving quickly and the security pitfalls of modern conveniences are often ignored. Public WIFI hotspots, common in airports and coffee shops, are a hackers dream because they offer streams of visible data waiting to be mined. Using a VPN keeps your information secure.

Deep Packet inspection is another growing concern. Many ISPs would like to analyze statistics from your online activities for marketing and routing purposes. Using a VPN thwarts efforts to conduct deep packet inspections.

Similarly, search engines and social networking sites, like Google and Facebook, are storing information about your online habits indefinitely. Since a VPN provides the user with a different IP address, these privacy invasions are also thwarted.

VPN services provide different gateway cities where the IP address assigned to your computer is located. This allows users to access websites only available to users from a certain country. This application is particularly important for travelers who need to access websites from their home country and for people living in regions rife with censorship, like China and Iran.
Protocols

PPTP is the most common VPN protocol. It uses TCP port 1723 and Generic Routing Encapsulation (GRE) to secure packets. The main advantage of PPTP is that all major operating systems and many smartphones can natively use PPTP without any additional software.

IPsec is a protocol suite developed with IPv6 and often used in conjunction with L2TP tunneling. IPSec VPN services usually require third party software. Associated licensing costs are one of the largest cons of IPsec.

SSL/TLS is the most common encryption protocol on the Internet. Many SSL VPN plans use the OpenVPN client. This free, multi-platform client and the vibrant community that supports it have helped SSL VPNs rise to prominence.

SSTP is the newest popular protocol. It transports PPP or L2TP packets through an SSL 3.0 channel. Since SSTP uses the common HTTPS port 443, it is hard to block in highly censored regions, like the Middle East. Unfortunately, SSTP is only available on Windows Vista and Windows 7 computers.