How you prevent anyone to spy on your internet data???

I have come across the term VPN a couple of times, but never searched it, until I saw it in protonmail (a secure Switzerland based email service which has built in end to end encryption and other security features which protect user privacy), launching as a service and decided to investigate a little more to see what the fuss is all about, mainly because I am so far satisfied from protonmail.

VPN (Virtual Private Network) a “tunnel” like encrypted connection between you the user and the VPN operator's remote server.
Most importantly, using a VPN service encrypts someone’s incoming and sending data, securing the internet connection, preventing someone to "spy” on you. Basically your ISP (Internet Service Provider) cannot see your data, while your IP is concealed appearing to have the IP of the VPN server.

Either it is some government wanting your data, NSA-like organizations or a random hacker, one cannot be secure enough these days. Unfortunately.

Looking at Proton VPN, they appear to be effective in the following situations

1. Securing an insecure internet connection
2. Hiding your browsing history from your ISP
3. Preventing data discrimination (A VPN service can help ensure net neutrality. Because all of your traffic is encrypted, your ISP will not be able to selectively throttle or slow down certain types of traffic)
4. Preventing Internet censorship
5. Safe file sharing and bit torrent use
6. Protection against VPN compromise
7. Protection against online tracking

They cannot guarantee

1. Make you fully anonymous online (Any VPN provider knows the true IP of the user. But in the case of Proton since they are Swiss based they cannot be forced to log user IP address, and therefore even though they technically have access to user IP addresses, they cannot be legally obligated to log it and turn it over. This is rather unique to Switzerland and one of the reasons they decided to base ProtonVPN in Switzerland.)
2. Bandwidth throttling (If your ISP decides to throttle your entire Internet connection, there is nothing that ProtonVPN can do to help you bypass that since the VPN connection to our servers is established over the connection provided by your ISP.
3. Sophisticated Censorship (sophisticated censorship programs can ALWAYS block VPN traffic if they want to. This is because like with the rest of the internet, VPN connections are established over TCP/IP, which means that an adversary can always block VPNs by simply blocking connections to the IPs of the VPN servers. Indeed, this is what Netflix and the Great Firewall of China is doing.)

There are many VPN services out there and since I want to be objective and fair, below is an indicative table of the best VPN services of 2017 from Pcmag. (Proton VPN was released just this month, so it is not included).

I believe protonVPN is worth mentioning and adds value for someone trying to make an informed decision.
In any case you can choose one that suits your own unique situation and needs.

References

1. ProtonVPN site
2. Pcmag by MAX EDD June 2017 (image)
3. Pexels CC0 (image)