IDLE is an integrated development environment for Python, which has been bundled with the default implementation of the language since 1.5.2b1. It is packaged as an optional part of the Python packaging with many Linux distributions. It is completely written in Python and the Tkinter GUI toolkit (wrapper functions for Tcl/Tk).

IDLE is intended to be a simple IDE and suitable for beginners, especially in an educational environment. To that end, it is cross-platform, and avoids feature clutter.

Its main features are:

Multi-window text editor with syntax highlighting, autocompletion, smart indent and other.
Python shell with syntax highlighting.
Integrated debugger with stepping, persistent breakpoints, and call stack visibility.

IDLE has been criticized for various usability issues, including losing focus, lack of copying to clipboard feature, lack of line numbering options, and general user interface design; it has been called a "disposable" IDE, because users frequently move on to a more advanced IDE as they gain experience.

Author Guido van Rossum says IDLE stands for "Integrated DeveLopment Environment", and since van Rossum named the language Python partly to honor British comedy group Monty Python, the name IDLE was probably also chosen partly to honor Eric Idle, one of Monty Python's founding members.