When you choose Python for software development, you choose a large language ecosystem with a wealth of packages covering all manner of programming needs. But in addition to libraries for everything from GUI development to machine learning, you can also choose from a number of Python runtimes—and some of these runtimes may be better suited to the use case you have at hand than others.
Here is a brief tour of the most commonly used Python distributions, from the standard implementation (CPython) to versions optimized for speed (PyPy), for special use cases (Anaconda, ActivePython), or for runtimes originally designed for entirely different languages (Jython, IronPython).