There are many different VPN protocols and OpenVPN is quite often considered to be one of them. But to understand correctly what OpenVPN really represents we should learn more about such terms as the "VPN protocol" itself.
Simply put, a protocol is a set of rules that define how different devices in one network communicate with each other. For example, when we are connecting to the Internet we use the Hypertext Transfer Protocol (also known as HTTP). This protocol makes it possible to pass data from the computer to the website and vice versa. VPN protocols are special. They are made for those who want to organize secure virtual private networks that can be used inside the company to pass confidential data.
OpenVPN is also considered to be a protocol because it helps to establish similar private networks that help to secure the data passed from one device to another.
But it is more correct to call OpenVPN an open-source implementation of VPN technology with an alike piece of software that together can compose a protected tunnel for sending data from one computer to another. OpenVPN helps to diminish the risks of losing any private information (and risks are quite high especially when we talk about public networks). That's why it is always recommended to connect to VPN before login into some critical internet resources and applications (mail, banking apps, etc.).
Nowadays, OpenVPN has a reputation of being next to the most popular and secure instruments that make it possible to deploy virtual private networks (even though a new protocol called Wireguard is trying hard to take this title away).
Another reason to use OpenVPN is its cross-platform essence. The protocol supports a lot of different platforms including Linux, Windows, FreeBSD, macOS, Solaris, etc.
OpenVPN creates a secure tunnel between the VPN client and VPN server, so there is a protected channel to pass any data through. While using VPN, the geolocation of the IP address is changed to the geolocation of the VPN server, so your actual geolocation becomes invisible "outside". And because of such technologies cybercriminals can't access your personal data or somehow harm it while processing by the server.
Also, your ISP can't see the data. That's why it is possible to connect to a VPN in case of avoiding blocked resources (like torrent trackers or social media in some countries). Furthermore, VPN is a great solution for those who want to give access to the corporate network for remote workers or create a common virtual network for different offices in different parts of the city/country/world.
When we talk about sending data through VPN we imply that protocol UDP is used which is much more performant than traditional TCP. But if it is necessary you can switch to TCP (sometimes this variant is preferred because of the instability of UDP).
Encryption of data passed through OpenVPN is possible thanks to an open-source software library called OpenSSL. And that's great news because OpenSSL is a powerful product that is widely used across different web servers around the world that are secured via HTTPS connection (at the moment, it is the most reliable technology of this type). Using such technologies provides support to any popular encryption algorithms like AES, Chacha2, Poly1305, Triple DES, SM4, MD5, SHA-2, SHA-3, BLAKE2, Whirlpool, RSA, Diffie-Hellman, Elliptic curve, and many more.
If you want to use OpenVPN you might want to create your own VPN server by deploying a special piece of software on the virtual private server that you have already rented and used. Or you can find active VPN services that use the protocol OpenVPN. That won't be a problem for you because most of the VPN providers use this technology. OpenVPN underlies most of the VPN services you might know. It happens because there are no reasons to use anything else (yes, OpenVPN is so powerful and useful that you'd also prefer to use it instead of other protocols). OpenVPN is not only secure but also performant and does not imply any vital disadvantages.
If you wish to create your own VPN server you have to start with downloading, installing, and configuring special software. It is quite hard and will take some time. But it will be paid off by a more robust, secure, and reliable platform because you'll be the one who controls all the processes, monitors traffic, etc. Nobody will be in charge of manipulating the data in any way. And nobody will have access to the server's inners. Moreover, you'll have to create a hardware and software platform that is always available and works without any failures. To make it possible you have to consider renting a reliable and fast server with unlimited bandwidth. And it is easy to find such a server. You can rent one on Hostman.
There is an easier way to start using OpenVPN (and, to be honest, more preferable in most cases) — paying for pre-configured VPN service (there are thousands of them). If you choose this variant, the only thing you have to do is to download a special VPN application, install it on your device and log in using the credentials you used while creating an account