Believe it or not, it's possible (and encouraged!) to use object-oriented programming (OOP) in plain-old C. Object-oriented code exhibits the qualities of abstraction, encapsulation, polymorphism, and inheritance, and these qualities can help make an application easier to write, debug, and change. In this talk, I'll demonstrate how to do achieve these qualities in C, ranging from the simple to the complex. This talk is based entirely on work I share publicly here: https://github.com/nathancharlesjones/Comparison-of-OOP-techniques-in-C.