As for any other libraries. Considering that C is almost 50 years old, there are an enormous amount of frameworks for C. Many of them are more or less obsolete while others have become part of various operating systems and their kernels, like OpenGL and those sockets. However, frameworks and libraries are not the same.
You create the categories by analyzing the data you collected in your research. Many times, your framework will focus on the customer and their needs. But a framework could also be about industry structure, the structure of a current service, or a major trend like the sharing economy.
So C frameworks are generally referred to as “libraries” instead. And the number of C libraries is endless. Two wellknown C libraries are OpenGL and TCP/IP sockets. OpenGL is a huge graphics framework that interacts with the GPU to render, draw and do a lot of other stuff and the API that OpenGL exposes is C based.