OpenVPN can create a virtual private network, which allows you to transfer data in a more secure way. Likewise, it can create a tunnel by which all data from a subnetwork or virtual Ethernet adapter are transferred over a single UDP or TCP port.
The program is actually a client that uses an online service to mediate between your device and other servers out there. Moreover, it can be used for remote access and site-to-site connections. Its graphical user interface makes it quite easy to use, despite the complicated process going on under the hood. Fortunately, the VPNs created are based on the SSL/TLS protocol, which ensures security with one of the tightest protocols available.
As a service, OpenVPN has various additional advantages. First, there are clients for various platforms, which makes it available regardless of the operating system you are using. In addition, it provides site-concrete customization. Finally, it has a modular design, allowing for different types of implementation.
To sum up, OpenVPN provides a secure way to communicate through a VPN tunnel without any cost. The only thing I did not like about it was the initial configuration, which requires various steps before you can actually connect through the VPN; and, unfortunately, the documentation is not very clear in this respect.