Since the original use of the Internet has changed, so it has been necessary to redevelop and improve its security structures. Vicious networks and users, commercialization, surveillance, censorship and “Man In The Middle” attacks have resulted in a need to rethink Internet security measures. A VPN service can act as protection against certain threats, but the level of protection will depend on the threat model. By identifying and considering the potential enemies, the nature of the information and the consequences of a security breach, you are able to formulate an appropriate threat model.
For example, users at public Wifi hotspots don’t need to remain anonymous but they would like to protect sensitive information. As a VPN server typically encrypts traffic between the devices and the VPN servers and so eavesdroppers will only see encrypted data, any VPN service would be adequate.
Sometimes a user may want to protect their privacy and anonymity from their ISP, so they are not associated with their online activity and the ISP cannot share this information. In this case, the VPN service needs to be more trustworthy than the ISP. Using a VPN service which uses forward secrecy and doesn’t retain logs is appropriate.
If a user doesn’t want websites to know their IP address, it can be possible to hide this using a VPN service. The VPN service will only allow the website to see the IP address of the exit server. Similarly, maintaining anonymity with email correspondents is possible, though extra cautionary measures may need to be taken.
A user may want to conceal their online activity and their identity from their ISP and the state. Here it’s best to employ a nested chain of VPN services or even connect anonymously through a public Wifi hotspot. This can also overcome censorship by the state.
For ultimate security, using Tor – ideally through a public Wifi hotspot - enables users to tunnel traffic through multiple anonymity structures. Effectively, it enables the user to remain anonymous while protecting the details of their online activity, so being resilient to censorship. Further, it is possible to tunnel JonDonym through Tor, tunnel a VPN service through JonDonym and use an instant-wipe hotkey for final encryption.
For further reading on whether a VPN can protect you please see this guide