Here's how to buy the best VPN for your own online security

We used to see the Internet as a free, open platform, but in the past five years that notion has been rendered obsolete. We are aware that government agencies and foreign security services can track where we go, what we do and who we talk to. We know that large corporations routinely monitor our activities when we use their services, and that we don't always control how they use this information - or to whom they give it. We may live in or visit countries that block services and censor content, or we may want to use streaming services that offer more in their home territories than in the UK. When we access the Internet over public wireless networks, there is always the risk that someone is spying on us.

Using a VPN, we can bypass these controls and restrictions. We can hide our location and break the IP address links that tie our online activities to a specific location. We can hide activities, making them harder to record or monitor. We can substitute our actual other location, allowing us to view censored content, access blocked services or use streaming services as if we were in another territory. While a VPN doesn't guarantee privacy - let alone anonymity - it's one of the best tools we have to preserve it.

What is a VPN?

VPN stands for virtual private network, and in its most basic form is a way to extend your private network to one or more public networks (such as the Internet), so you can send and receive data securely as if you were physically connected to a private network. When someone talks about connecting to a company's VPN, for example, what they mean is that they have a secure way to connect to the company's network as if they were sitting in the office. All data sent back and forth is secure and encrypted, and it's difficult for outsiders to eavesdrop.

VPN services, however, mean something a little different. Here, you use the same basic method to create a secure connection between your device or computer and servers belonging to the VPN provider. All network traffic goes through this connection, so no one can see it until it leaves the VPN server and goes to the public Internet. This has two effects. First, it keeps your activities and communications private. Even your ISP can't see or record what you're doing. Second, it hides where you are - thus protecting your identity - while making it appear as if you are at the location of the server. You may live in Glasgow, but it looks like you're connecting from Finland, Maryland or the Bahamas. Only you and your VPN provider know for sure.

Read also: What is a VPN?

Why use a VPN?

Many people are either comfortable with the idea that their online activity is being tracked, blocked or censored - or they just don't know or care. For the rest of us, there are three good reasons why we might want to use a VPN:

• Privacy: While using a VPN won't necessarily give you anonymity online, it makes it much easier to hide your activities and harder to identify. This is an advantage for those who feel uncomfortable with government or corporate spying, but an absolute necessity for whistleblowers, activists and those living under oppressive regimes.
• Safety: If you're using public Wi-Fi, say, at a hotel or coffee shop, or if you can't guarantee the security of other networks over which you connect, using a VPN provides an extra layer of protection for accessing sensitive services or conducting business while you're away from the office.
• Access: The country you live in or plan to visit may block access to certain websites or online services - including social networking sites such as Facebook and Twitter. Increasingly, major ISPs are doing the same, although generally the sites contain pornography, piracy or illegal material. What's more, some sites and services - including video streaming services such as Hulu or Netflix - have controls to ensure that non-U.S. users can't access content in the U.S., which is a shame if your country doesn't have a service or if the U.S. service is better. Using a VPN can bypass these blockades.

Are all VPNs essentially the same?

No. Some are inconvenient and technical to use, while others are extremely simple. Some have a large number of servers spread around the world, while others have only a few in very specific territories. This will affect where you can look to connect from, as well as the number of users the service can handle before the servers become overloaded and slow down connections.

There are also huge differences in terms of performance. Using a VPN will result in a drop in Internet speeds, as all traffic must be routed through the network and VPN servers. Some VPN services have invested in their technology and network, so the impact isn't always noticeable, but others will see your speeds drop to the point where you'll have difficulty streaming video anyway.

What about privacy and security? Are they all equally private and secure?

Again, no. First, a VPN provider can log and even monitor your traffic, with some free VPN services known to aggregate and sell some mostly harmless user data. The trick is to see if your provider logs your traffic, what it does with it, and how long it keeps the logs. Many are now claiming that they keep no logs, but - frankly - there is no way to know for sure.

Otherwise, the provider's home location is a key factor. In some countries, such as the United States or the United Kingdom, the government and security services have greater powers to request logs or monitor incoming and outgoing traffic; powers that the average VPN provider will not be able to resist. If privacy or anonymity is your main reason for using a VPN, consider finding one based in a country outside the "fourteen eyes" countries that routinely cooperate on surveillance and commercial information - the United Kingdom, United States, Australia, Canada, New Zealand, Denmark , France, Netherlands, Norway, Germany, Belgium, Italy, Spain and Sweden - especially the first five that make up the core group of "five eyes."

Finally, different VPNs use different encryption protocols, some more or less secure than others, some have a greater impact than others on speed. OpenVPN, Chameleon and SSTP offer the best balance between performance and security. PTTP is fast, but potentially weaker.

Besides security and performance, are there any other features I should pay attention to?

Some VPN services offer additional protections, including "double-hopping," which further hides your location and identity, or DNS leak protection to prevent your browser from sending DNS requests - requests to direct you to a specific URL - directly to your ISP rather than through the VPN , revealing your true location. Some have gateway bypassing and monitoring features on public wireless networks, while others allow you to turn your personal computer or laptop into a virtual router, so you can connect through it to other devices so they all use the VPN.

Another useful feature is the emergency shutdown switch. Configure this for specific applications, such as the browser, and if the VPN connection fails, the browser will shut down automatically, preventing sudden disclosure.

What about restrictions or limitations?

Not all VPNs work equally well in different countries. Some may not work, say, in China, where the Great Firewall, which prevents Chinese citizens from accessing unapproved sites and content, has become particularly good at detecting and blocking VPNs. Similarly, Netflix can now detect multiple VPNs and prevent them from being used to access the service in the US. Just because one works one day doesn't necessarily mean it will work in the future.

P2P and Torrents are often subject to restrictions. Some services simply don't allow torrents or P2P traffic to be shared or downloaded over a VPN, while others may restrict this ability. Again, if this is your bag - and we're sure you wouldn't dream of sharing content illegally - check what the provider allows before signing up.

Finally, check how many devices you can use through the service and whether the service supports all the devices you want to use. Many will let you use the VPN on up to five PCs, Macs or other devices, while others are limited to just one. Also, not all support the full range of devices, so if you need something for a Windows laptop, iPad, Android smartphone and Kodi streamer, shop around and narrow down your options.

If you're looking for the best VPN service, check out ExpressVPN.