The Python window is an efficient and convenient location to use geoprocessing tools and Python functionality from within ArcGIS. The Python commands run from this window can range from single lines of code to complex blocks with logic. The Python window also provides a place to access additional functionality using custom or third-party Python modules and libraries.
The Python window also acts as a gateway to Python for those new to scripting, providing an intuitive interface that makes learning Python scripting in ArcGIS as easy as possible. In the Python window, various tool and method usage and syntax can be viewed or experimented with, and snippets of Python code can be entered or pasted into the window to test scripting ideas outside a stand-alone script. The Python window is a powerful mechanism for efficiently accessing and executing geoprocessing and scripting tasks and increasing productivity by placing Python functionality within ArcGIS for Desktop applications.
Opening the Python window
The Python window can be opened within any ArcGIS for Desktop application by clicking the Python window button 
on the Standard toolbar.
Below shows how the Python window appears when first opened:
An overview of the Python window
Once opened, the Python window can be moved by clicking the bar at the top and dragging to your preferred location. The window can be docked or undocked.
The window prompts for the next command with the primary prompt, three greater-than signs (>>>), and continuation lines prompt with the secondary prompt, three dots (...).
Continuation lines are needed when entering a multiline construct. See the following example using an if statement:
The Python window contains two sections:
- The Python section on the left. This is where commands are entered.
- The Help section on the right. This is where command usage, help, and execution messages are viewed. This section can be hidden or placed to the right, left, top, or bottom of the Python section.