PyMOL can produce high-quality 3D images of small molecules and biological macromolecules, such as proteins. PyMOL is one of a few open-source model visualization tools available for use in structural biology. The Py part of the software's name refers to the program having been written in the programming language Python. PyMOL uses OpenGL Extension Wrangler Library (GLEW) and FreeGLUT, and can solve Poisson–Boltzmann equations using the Adaptive Poisson Boltzmann Solver.[2] PyMOL used Tk for the GUI widgets and had native Aqua binaries for macOS through Schrödinger, which were replaced with a PyQt user interface on all platforms with the release of version 2.0.