This section will provide a quick introduction to the basics of OpenGL. It's next to impossible to meaningfully summarize all the nooks and crannies of the standard here; hence it is "unscientific," superficial.
OpenGL is a popular low-level graphical API. It's standardized and almost ubiquitous. Desktop and mobile operating systems commonly ship with an implementation of OpenGL (in the case of mobile, OpenGL ES, a feature-restricted subset of the standard; here, ES stands for embedded systems). Modern web browsers also implement a variant of OpenGL ES called WebGL.
Wide distribution and a well-defined compatibility makes OpenGL a good target for cross-platform apps, especially video games and graphical toolkits. Kivy also relies on OpenGL to perform rendering across all the supported platforms.