swf.wtf
Feb 25, 2026 guide python beginner reference

Python for Beginners.
// setup to first real project.

A practical guide you can keep open while learning. Focus on commands and habits you will actually use.

$ python --version
Python 3.12.x
$ python main.py
hello, world
$ _
// contents
Install Python First script Virtual environments Packages with pip Core syntax Data structures Functions Files and JSON Errors and debugging Project layout Practice plan Cheat sheet

Install Python

Use Python 3.11+ if possible. Newer versions are faster and better supported.

fedora 
sudo dnf install -y python3 python3-pip
python3 --version
ubuntu / debian / mint 
sudo apt update
sudo apt install -y python3 python3-pip python3-venv
python3 --version
arch 
sudo pacman -S python python-pip
python --version
// command name note
Some systems use python3, others use python. In this guide I use python. If that fails, swap it to python3.

First script

hello.py 
print("hello, world")
name = "steve"
print(f"hi {name}")
run 
python hello.py

Virtual environments

Always use a virtual environment per project. It avoids dependency conflicts between projects.

create and activate 
mkdir python-demo
cd python-demo
python -m venv .venv

# Linux/macOS
source .venv/bin/activate

# Windows PowerShell
.venv\Scripts\Activate.ps1
deactivate 
deactivate
// do this early
Create and activate .venv before installing packages.

Packages with pip

common commands 
python -m pip install requests
python -m pip install -U pip
python -m pip list
python -m pip freeze > requirements.txt
python -m pip install -r requirements.txt
// why python -m pip
It guarantees pip belongs to the Python interpreter you are currently using.

Core syntax

Variables and types

name = "Ada"
age = 28
height = 1.72
is_admin = False

print(type(name))

Conditionals and loops

if age >= 18:
    print("adult")
else:
    print("minor")

for i in range(3):
    print(i)
// biggest beginner gotcha
Indentation is syntax. Use consistent spaces (4 spaces per level is standard).

Data structures

list / dict / set / tuple 
langs = ["python", "go", "rust"]
user = {"name": "steve", "role": "dev"}
tags = {"linux", "python"}
point = (10, 20)

langs.append("bash")
print(user["name"])

Functions

functions.py 
def greet(name: str) -> str:
    return f"hello, {name}"

def area(width: float, height: float) -> float:
    return width * height

print(greet("steve"))
print(area(3, 5))

Files and JSON

read and write text 
with open("notes.txt", "w", encoding="utf-8") as f:
    f.write("learn python\n")

with open("notes.txt", "r", encoding="utf-8") as f:
    print(f.read())
json 
import json

data = {"name": "steve", "score": 99}

with open("data.json", "w", encoding="utf-8") as f:
    json.dump(data, f, indent=2)

with open("data.json", "r", encoding="utf-8") as f:
    loaded = json.load(f)
    print(loaded["score"])

Errors and debugging

try/except 
try:
    value = int("42")
except ValueError as exc:
    print("bad number:", exc)
else:
    print(value)
debugging basics 
python -m pdb app.py        # step debugger
python -m pip install ruff   # fast linting
ruff check .

Project layout

starter layout 
my_project/
  .venv/
  src/
    main.py
  tests/
    test_main.py
  requirements.txt
  README.md
  .gitignore
// .gitignore minimum
Add .venv/, __pycache__/, and *.pyc so generated files do not get committed.

Practice plan (7 days)

Cheat sheet

daily python commands 
python --version
python file.py
python -m venv .venv
source .venv/bin/activate
python -m pip install package
python -m pip freeze > requirements.txt
python -m pip install -r requirements.txt
deactivate
// next step
After this guide, pick one small project and finish it end to end. That is where Python sticks.