A Virtual Private Network (VPN) is a network technology that provides a secure tunnel -- for a device connected to the Internet -- that aims to protect online traffic from being blocked, censored or snooped upon. The primary reasons for using a VPN include: to avoid geographical blocks, to secure data, to protect against WiFi vulnerabilities, and to combat surveillance. A Virtual Private Network (VPN) allows Internet connected devices to change their IP address -- 32-bit decimal number or 128-bit hexadecimal number that typically provides a rough geolocation of where a device is connected to the Internet -- to one that hides their actual geographical location; such as changing a UK IP address to a Japanese IP address. A Virtual Private Network (VPN) typically uses 256-bit encryption to encrypt data between a Internet connected device (computer) and the VPN server; this level of encryption would take modern supercomputer billions of years to brute force unlock a 128-bit-encryption key.
VPNs provide their encryption standard and data transmission through the
use of a VPN protocol. The most common VPN protocols (currently in use) are:
PPTP, L2TP/IPSec, SSTP, IKEv2/IPSec, OpenVPN, IPSec, Wireguard and SoftEther.
The different VPN protocols have their pros and cons: some are more secure
than others (some protocols are believed to have been compromised by national
security services); they differ on resource usage (cpu use); some are available
on more platforms; they differ on how easy they are to setup; and they differ
on their ability to bypass firewalls. OpenVPN is one of the most popular VPN
protocols, it can be used over the Internet transmission protocols TCP and
UDP, and on the following platforms: Linux, Solaris, OpenBSD, NetBSD, FreeBSD,
QNX, Windows and macOS. The following VPNs are believed to use or have used
OpenVPN: NordVPN, ExpressVPN, PrivateVPN and VPNArea. VPNs can also provide
a variety of VPN protocols for their users to choose from: CactusVPN, for
example, allows its users to select from the following VPN protocols: OpenVPN,
SSTP, SoftEther, IKEv2, PPTP or L2TP/IPSec. It is difficult to conclude which
VPN protocol is "best", as they all perform well in certain aspects.
It is generally believed that Virtual Private Networks began with the creation of the Point-to-Point Tunneling Protocol (PPTP). The Point-to-Point Tunneling Protocol (PPTP) is specified in the Request for Comments 2637: published in 1999, its authors were: K. Hamzeh (Ascend Communications); G. Pall (Microsoft Corporation); W. Verthein (3Com); J. Taarud (Copper Mountain Networks); W. Little (ECI Telematics); and G. Zorn (Microsoft Corporation). The purpose of PPTP was to create a secure tunnel for employees of large businesses and corporations (to work from home, or to connect from smaller offices to head office etc). VPNs for personal use slowly increased in availability and usage when China implemented their Great Firewall of China (GFW) to block access to western websites like Google and Youtube, and when Edward Snowden leaked the mass surveillance programs of the western intelligence community.
While the criticism of Virtual Private Networks is fairly mild when it comes to users using them to circumvent geo-blocks of Netflix, ifollow, Google, BBC iPlayer, Hulu and NOW TV, the scrutiny and criticism has increased when it comes to users using VPNs to: download copyrighted materials (via torrents etc); participate in trolling/harassment; and accessing illegal content. It has led to China promising to block all VPNs (source: BBC's "China's Internet Privacy Clampdown"). The UK government has also warned against the use of end-to-end encryption, with the Guardian reporting in 2017 that Home Secretary Amber Rudd said: "don't provide a secret place for terrorists to communicate with each other". While this was primary a criticism of end-to-end Encryption employed by messaging apps, it potentially shows the unease western governments may have in regards to VPNs.
In conclusion, the future of VPNs appears bright, with usage statistics indicating that nearly a quarter of Internet users used a VPN in 2019 (source: statista.com) and that this number is projected to increase by 10% by 2022. Currently the most popular VPNs are: NordVPN, CyberGhost, ExpressVPN, PrivateVPN, Surfshark, IPVanish, VyprVPN, CactusVPN, HideMyAss!, ZenMate, PureVPN, SaferVPN and UltraVPN. The majority of VPNs come with a monthly or annual fee; there is usually a discount for purchasing annually rather than monthly. Some VPNs provide a free amount of data per month: VPNs that have provided a free VPN service (download limit per month is typical) include: TunnelBear, Windscribe, ProtonVPN and Hide.me.