Python Basics · Getting Started · Lesson 3 of 36
Running Python Files
Concept
Running Python Files
Python files end in .py and run top-to-bottom with the python filename.py command, or right here in the browser editor.
Indentation in Python isn't just a style choice — it's how the language knows which lines belong to which block, so consistent spacing (usually 4 spaces) actually matters for the code to run at all.
By the end of this lesson
- Explain the core idea behind Running Python Files.
- Predict output before running a change.
- Test one realistic and one unusual input.
- Use the result to make the next decision.
How to study this page
- 1. Read one concept.
- 2. Change the example.
- 3. Run, compare, and explain.
- 4. Complete the challenge below.
Self-check before continuing
Without looking at the example, describe what changes when you modify one input in Running Python Files. Then reopen the editor and prove your explanation with a small test.
You are ready to continue when you can predict, test, and explain the result.
Your turn
Write a two-line script that stores your name in a variable and prints a greeting.
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Console