Two ways to run Python

The interactive shell

The first way is the REPLREPLRead, Evaluate, Print, Loop: Python waits for a line, runs it, shows the result, and waits again. Also called the interactive shell.. You start it by typing Python's name in the terminal with nothing after it.

python

python3

python3

The prompt changes to >>>. That's Python waiting for you. Type a line, press Enter, and it answers straight away:

>>> 3 + 4
7
>>> "Selam"
'Selam'
>>> print("Selam")
Selam

You didn't need print to see 7. The shell shows the value of whatever you type, and shows text with its quotes so you can tell text from numbers. Python 3.14's shell also colors your code as you type. When you're done, type exit() and press Enter to get back to the normal terminal.

The shell is good for quick questions: "what's 15% of 1,200?", "does this line work?". But nothing you type is saved. Close the window and it's gone.

Where am I: the terminal or Python?

The most common beginner mix-up is typing into the wrong place. Look at the start of the line. The terminal's prompt usually ends in >, $, or %, often after a folder name, like PS C:\Users\Hana> or hana@MacBook-Air ~ %. Python's prompt is exactly three arrows, >>>, with nothing before them.

Terminal commands only work at the terminal prompt. Python code only works after >>>. Here's what happens when a terminal command goes to Python:

Programs saved in files

The second way is a scriptscriptA program saved in a file ending in .py, run from top to bottom. Also called a Python file.: a file ending in .py that holds your whole program. Python runs it from the first line to the last and then stops. Almost everything you build in this course will be a script.

Scripts don't echo values the way the shell does. Only what you print appears. The code boxes on this site run your code as a script, so you can see this here. Decide first: what does this print?

3 + 4
print(3 + 4)

7

Now run it, then add print(...) around the first line so both results appear.

3 + 4
print(3 + 4)

The shell and the script are the same Python. The same line gives the same result; the only difference is that the shell shows every value, and a script shows only what you print.

Running a file

Open your python-course folder in VS Code. In lesson 0.2 you saved setup_check.py there; if you didn't, create it now: File, then New File, type print("Selam"), and save it as setup_check.py.

You can run it in two ways.

1. From the terminal

   In VS Code, choose Terminal, then New Terminal. It opens inside your folder. Type the command for your system:

   WindowsmacOSLinux

   Windows

   python setup_check.py

2. With the Run button

   With the file open, click the triangle Run Python File button at the top right of the editor. VS Code types a similar command into its terminal for you.

Either way, the terminal shows your program's output and returns to the prompt.

Which one to use

Use the shell to try one small thing and see the answer immediately. Use a script for anything you want to keep, run again, or build on. Most programmers keep both open: a script they're writing, and a shell for checking ideas.

A good rhythm while you learn: when you're unsure what a line does, try it in the shell or in a code box here. Once it does what you want, copy it into your script.