What Is a VPN?

VPN literally stands for virtual private network. With a VPN, all your traffic is held inside a private, encrypted tunnel as it makes its way through the public internet. You don't access the destination until after you've reached the end of the VPN tunnel.

The root of why VPNs are popular is because they can be used to anonymize and encrypt internet traffic. Governments, ISPs, wireless network hackers, and others can not only not see what's inside a VPN but also usually not even be able to find out who is using it.​

One reason a VPN might be used is in a work environment. A mobile user who needs access to information from a work server might be given VPN credentials to log in to the server when away so that he can still access important files.

Other types of VPNs include site-to-site VPNs, where one entire local area network (LAN) is joined or connected to another LAN, such as satellite offices connected together in one corporate network over the internet.

Probably the most common use for a VPN is to hide your internet traffic from agencies that can gather your information, such as ISPs, websites or governments. Sometimes, users who are obtaining files illegally will use a VPN, like when accessing copyright material through torrent websites.

Everything you do on the internet has to pass through your own ISP before reaching the destination. So, when you request Google, for example, the information is sent, unencrypted, to your ISP and then through some other channels before reaching the server that holds Google's website.

During this transmission to the server and back, all of your data can be read by the ISPs that are used to process the information. Each of them can see where it is you're using the internet from and what website you're trying to reach. This is where a VPN comes in: to privatize that information.

When a VPN is installed, the request to reach any website is first encapsulated in what we'll visualize as an enclosed, sealed up tunnel. This happens the moment you connect to the VPN. Anything you do on the internet during this type of setup will appear to all the ISPs (and any other inspector of your traffic) that you're accessing one single server (the VPN).

They see the tunnel, not what's inside. If Google were to inspect this traffic, they'd see not who you are, where you're from or what you're downloading or uploading, but instead just a single connection from a particular server.

Where the meat of a VPN's benefit comes into play is what happens next. If a website like Google were to reach out to the requester of their website (the VPN) to see who it is that was accessing their server, the VPN can either respond with your information or deny the request.

The determining factor in this decision is whether or not the VPN service even has access to this information. Some VPN providers purposefully delete all user and traffic records or refuse to record the logs in the first place. With no information to give up, VPN providers provide complete anonymity for their users.

VPN implementations can be software-based, as with Cisco's VPN client and server software, or a combination of hardware and software, like Juniper Network's routers that are compatible with their Netscreen-Remote VPN client software.

Home users can subscribe to a service from a VPN provider for a monthly or yearly fee. These VPN services encrypt and can anonymize browsing and other online activities.

Another form is SSL (Secure Sockets Layer) VPN, which allows the remote user to connect using just a web browser, avoiding the need to install specialized client software. There are pros and cons to both traditional VPNs (typically based on IPSec protocols) and SSL VPNs.