Creating and Running .py Files

Write your Python code in a text editor and save the file with a .py extension. Save the file using the UTF-8 character encoding.

sample_hello.py

name = 'Okabe Rintaro'
age = 18

print('Name:', name)
print('Age:', age)

if age >= 20:
    print('Adult.')
else:
    print('Minor.')

Write Python code directly in the text file and save it like this. Use 4 spaces (or tabs, as long as they are consistent) for indentation.

You can write comments (notes) in a .py file. Comments are ignored by the Python interpreter, so they are useful for leaving descriptions or notes about the code.

# A script that displays user information.

def greet(name, age):
    '''A function that receives a name and age and displays a greeting.'''
    print('Name:', name)
    print('Age:', age)

greet('Makise Kurisu', 18)

A string enclosed in """ or ''' written immediately below a function is called a docstring and is used as a description of the function. The # symbol is widely used for inline code comments.

Open a terminal (macOS / Linux) or command prompt (Windows), navigate to the directory where the .py file is saved, then run it.

Run on macOS / Linux

Use the python3 command on macOS and Linux.

python3 hello.py

Name: Okabe Rintaro
Age: 18
Minor.

Run on Windows

Use the python command on Windows.

python hello.py

Name: Okabe Rintaro
Age: 18
Minor.

If Python is not installed, see Setup.

A .py file is simply a plain text file. You can create one by writing Python code in a text editor and saving it with a .py extension. No special tools are needed.

Saving the code to a file means you can run the same code any number of times. It also makes it easier to manage longer code.

Use python3 on macOS / Linux and python on Windows. Depending on the environment, both commands may work.

For recommended editors and Python installation instructions, see Setup.