Python is an interpreted language,, meaning that its instructions are processed by a program known as an interpreter. This means that there is not a separate step for programmers to first compile their source code into an executable, which is required for many programming languages. There are many different programs that can interpret Python code, but the default interpreter (known formally as CPython, since it is written in C) is conventionally called python, although on some systems, interpreters might be named python3, python3.7, python2, python2.7, etc., in order to distinguish between different versions. (And on other systems, multiple versions might be named python, with priority in a user's PATH dictating which gets executed when that command is called.) In addition to the default python interpreter, there is an additional third-party interpreter named ipython that provides enhanced functionality in interactive sessions. The ipython interpreter also serves at the core of Jupyter notebooks running python, supporting a number of "magics" that lie outside of the core Python language but provide useful functionality in those more interactive environments.

Python is a programming language with a set of built-in objects and rules for describing and transforming those objects, a program — that is, an interpreter — that processes code written in the Python language, and a vast ecosystem of packages and tools that have sprung up to support work in a wide variety of problem domains and disciplines. In this tutorial, we will focus mostly on the language and on the use of the interpreter.