Python Tutorial

Python Introduction

Learn what Python is, why it's popular, and what you can do with it.

What is Python?

Python is a popular programming language created by Guido van Rossum and released in 1991. It is used for:

  • Web development (server-side)
  • Software development
  • Mathematics and data analysis
  • System scripting
  • Machine learning and artificial intelligence

What can Python do?

  • Python can be used on a server to create web applications
  • Python can be used alongside software to create workflows
  • Python can connect to database systems and read and modify files
  • Python can be used to handle big data and perform complex mathematics
  • Python can be used for rapid prototyping or production-ready software development

Why Python?

  • Python works on different platforms (Windows, Mac, Linux, Raspberry Pi, etc)
  • Python has a simple syntax similar to the English language
  • Python has syntax that allows developers to write programs with fewer lines than some other programming languages
  • Python runs on an interpreter system, meaning that code can be executed as soon as it is written
  • Python can be treated in a procedural way, an object-oriented way or a functional way

Python Syntax compared to other programming languages

  • Python was designed for readability, and has some similarities to the English language with influence from mathematics
  • Python uses new lines to complete a command, as opposed to other programming languages which often use semicolons or parentheses
  • Python relies on indentation, using whitespace, to define scope; such as the scope of loops, functions and classes

Example

print("Hello, World!")

How Python Runs Your Code

Python is an interpreted, dynamically typed language. You write plain-text .py files, and the Python interpreter reads them top to bottom, compiles them to intermediate bytecode, and executes that on the Python Virtual Machine (PVM). There is no separate compile step to manage — you run the file and see results immediately.

  • Interpreted: run code as soon as you write it, great for learning and prototyping.
  • Dynamically typed: you do not declare variable types; Python infers them at runtime.
  • High-level: memory management and many low-level details are handled for you.

Python 2 vs Python 3

Always use Python 3. Python 2 reached end-of-life in 2020 and no longer receives security updates. The classic difference beginners hit:

# Python 3 (correct today)
print("Hello, World!")     # print is a function

# Python 2 (obsolete)
# print "Hello, World!"    # print was a statement

Check your version any time with python --version.

Python vs Other Languages

FeaturePythonJava / C++
Line endingNewlineSemicolon ;
Blocks / scopeIndentationCurly braces
TypingDynamicStatic (declared)
Compile stepRun directlyCompile then run
"Hello World" lines13–5

Try It Yourself

Exercise 1: Write a program that prints your name and your favourite programming reason on two separate lines.

Show solution
print("Ada Lovelace")
print("I like that Python reads like English.")

Exercise 2: In one print call, output Python is fun! exactly, including the exclamation mark.

Show solution
print("Python is fun!")

Key Takeaways

  • Python is high-level, interpreted, and dynamically typed.
  • It is prized for readable, English-like syntax and fast development.
  • Always use Python 3; print() is a function.
  • Indentation — not braces — defines code blocks.

📘 Real-World Deep Dive

Python's "batteries included" philosophy makes it the default language for scripting, data engineering, ML, automation, and web back-ends. Knowing its shape — indentation, dynamic typing, rich stdlib — pays off on every codebase you'll ever touch.

Real-Life Scenario

A small data-engineering script that reads a CSV, aggregates totals per user, and writes a JSON report — the classic first-week-on-the-job task.

Real-Life Example

import csv, json, sys
from collections import defaultdict
from pathlib import Path

def build_user_totals(csv_path: Path) -> dict[str, float]:
    totals: dict[str, float] = defaultdict(float)
    with csv_path.open(newline="") as f:
        reader = csv.DictReader(f)
        for row in reader:
            user = row["user"]
            amount = float(row["amount"])
            totals[user] += amount
    return dict(sorted(totals.items(), key=lambda kv: -kv[1]))

def main(in_path: str, out_path: str) -> int:
    totals = build_user_totals(Path(in_path))
    Path(out_path).write_text(json.dumps(totals, indent=2))
    print(f"wrote {len(totals)} users to {out_path}", file=sys.stderr)
    return 0

if __name__ == "__main__":
    sys.exit(main(*sys.argv[1:]))

Expected Output

{"alice": 240.5, "bob": 110.0, "carol": 75.25}

Common mistakes

  • Forgetting the if __name__ == "__main__": guard makes the script run side-effects on import, which silently breaks tests.
  • Mixing tabs and spaces in indentation raises an IndentationError the very first time the file is opened in a different editor.
  • Reading the whole CSV with list(...) loads gigabytes into RAM — use csv.DictReader and stream rows.

🚀 Performance & Best Practices

  • Use pathlib.Path instead of os.path.join — chained methods compose and read better.
  • Prefer defaultdict or Counter over manual dict.setdefault for aggregation.
  • For JSON > 100 MB consider ijson or orjson instead of the stdlib encoder.

🧪 Try It Yourself

  1. Rewrite build_user_totals to also return the per-user transaction count alongside the total.
  2. Add a --since YYYY-MM-DD flag that filters rows by date before aggregating.
  3. Convert the script into a click-style CLI with a help message.

FAQ: Python Introduction

Common questions about this page.

What is Python Introduction?

Python Introduction is a Python Tutorial lesson that explains python introduction in Python. Learn what Python is, why it's popular, and what you can do with it. Copy the samples and run them in the Python editor. It is written for beginners who want a clear definition and working examples.

Should I run python introduction examples locally for better learning?

Yes. Use the browser editor on StudyGrid for a quick check, then Download the example and run it on your computer. Local runs show real errors and the real toolchain, which is one of the fastest ways to learn python introduction in this Python Tutorial Python lesson (Python Introduction).

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What is the syntax of python introduction?

This Python Introduction tutorial shows python introduction syntax with short Python examples. Use the code blocks in this lesson for the exact statements, then try them in your editor.

Python Introduction example for beginners

Yes. This page includes a beginner python introduction example you can copy and run. It is designed for searches such as "python introduction for beginners", "python introduction example", and "how to use python introduction".

What are common mistakes with python introduction?

Common python introduction mistakes include wrong syntax, mixing types, and skipping practice. Work through this Python Tutorial chapter in order, run every example, and check the output before moving on.

Why should I learn python introduction?

Python Introduction is used in real Python work. Learning python introduction helps you write clearer programs and continue the Python Tutorial tutorial on StudyGrid.

Is Python Introduction free to learn online?

Yes. You can learn python introduction free on StudyGrid (studygrid.in). This chapter is part of the Python Tutorial path and includes examples, syntax, and next-step links.