Python

Python is a high-level, general-purpose programming language created by Guido van Rossum and first released in 1991. It is dynamically typed, uses indentation to define blocks, and is usually run by an interpreter called CPython.

Why it matters

Python is one of the most widely used languages for scripting, web back ends, automation, data analysis and machine learning. Its readable syntax shortens the path from idea to working code, and a huge ecosystem of packages on PyPI covers most common needs. The trade-off is raw speed: CPython is slower than compiled languages for CPU-heavy work, so performance-critical parts are often written in C or Rust and called from Python.

Example

import json

with open("sites.json") as f:
    sites = json.load(f)

for site in sites:
    print(site["name"], len(site["name"]))

This reads a JSON file and prints each name with its length. There are no type declarations or braces, and the with block closes the file automatically.

Common mistakes

• Mixing tabs and spaces, which raises an indentation error.
• Using a mutable default argument such as def f(x=[]), which is shared between calls.
• Assuming Python 2 and Python 3 are compatible; Python 2 is end-of-life.

Related

• Interpreter
• Package manager
• Variable
• Garbage collection

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