We have tested each of these services in as repeatable a manner as possible, but it's worth remembering that networks can be fickle. To get the clearest picture of a VPN's performance, we would have to perform these tests many more times, at different locations and different times of day. We think of these tests as more of a snapshot of performance that establishes a replicable metric for measuring each service. Your mileage with these services will almost certainly vary somewhat from mine.
The user’s certificate could be stored on the VPN client computer or in an external smart card. In either case, the certificate cannot be accessed without some form of user identification (PIN number or name/password credentials) between the user and the client computer. This approach meets the something-you-know-plus-something-you-have criteria recommended by most security experts.
When we test VPNs, we generally start with the Windows client. This is often the most complete review, covering several different platforms as well as the service's features and pricing in depth. That's purely out of necessity, since most of our readers use Windows (although this writer is currently using a MacBook Air). We currently use a Lenovo ThinkPad T460s laptop running the latest version of Windows 10. We periodically upgrade to a newer machine, in order to simulate what most users experience.
Max Eddy is a Software Analyst, taking a critical eye to Android apps and security services. He's also PCMag's foremost authority on weather stations and digital scrapbooking software. When not polishing his tinfoil hat or plumbing the depths of the Dark Web, he can be found working to discern the 100 Best Android Apps. Prior to PCMag, Max wrote... See Full Bio

Some VPN services provide a free trial, so take advantage of it. Make sure you are happy with what you signed up for, and take advantage of money-back guarantees if you're not. This is actually why we also recommend starting out with a short-term subscription—a week or a month—to really make sure you are happy. KeepSolid VPN Unlimited offers a one-week Vacation subscription, for example. Yes, you may get a discount by signing up for a year, but that's more money at stake should you realize the service doesn't meet your performance needs.
One of today’s leading VPN providers and another worthy mention on our list of top 20 VPN services, PureVPN is known for its service quality and customer support. The service has 450 servers in 101 countries, allowing users to surf the Internet and use any online solution without having to reveal their IP address. This is very useful to those who want to bypass Internet censorship.
A VPN client on a remote user's computer or mobile device connects to a VPN gateway on the organization's network. The gateway typically requires the device to authenticate its identity. Then, it creates a network link back to the device that allows it to reach internal network resources -- e.g., file servers, printers and intranets -- as though the gateway is on the network locally.

Last on our fastest VPN list is OpenVPN, which is a blend of highly secured encryption keys, up to 256-bit session, and fast VPN nodes. It is an open source application that utilizes OpenSSL library SSLv3/TLSv1 protocols. OpenVPN uses both UDP and TCP protocols where UDP is faster while TCP is best known for breaking the firewalls. The downside of OpenVPN is that it doesn’t support any platform, but with the help of third-party softwares, you can install a fast VPN connection on your desired OS/Device.

Think about it this way: If your car pulls out of your driveway, someone can follow you and see where you are going, how long you are at your destination, and when you are coming back. They might even be able to peek inside your car and learn more about you. With a VPN service, you are essentially driving into a closed parking garage, switching to a different car, and driving out, so that no one who was originally following you knows where you went.
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