How to Run Python Scripts in Windows: From IDLE to Command Prompt

Anyone who has encountered Python knows there are several ways to run a Python script, such as in an interactive environment, from a command‑line window, or via an IDE, and the method can differ across operating systems. This article demonstrates the basics of running Python on Windows using the interactive environment.

After installing Python, you can enter the interactive environment in two ways. The first is to open IDLE, which provides a built‑in interactive window:

The second method is to open the Start menu, type cmd, launch the command prompt, type python and press Enter to reach the interactive prompt:

At the >>> prompt you can type statements one by one; the environment evaluates each line and displays the result, similar to a calculator. The special variable _ holds the result of the last expression, which can be reused in subsequent calculations. Variables must be defined before use; otherwise a NameError occurs, as shown in the example where a is undefined while length and width are defined.

If a syntax error occurs, Python reports the error line and message, helping you quickly locate and fix the problem.

Commands entered in the interactive session are not saved after the window is closed. However, you can recall previous commands with the up‑arrow key during the session; this history is lost once the session ends.

For longer programs, using the command line becomes inconvenient. You can create a script with a text editor. In IDLE, choose File → New Window to open a new editor window:

When writing code, pay careful attention to indentation, as Python relies on it to define code blocks. After writing, save the file with a .py extension (Ctrl+S). Press F5 to run the script, or right‑click and choose Run . The output will appear in the IDLE window.