Question 1

Why use virtual environments?

Accepted Answer

**Target Audience:** Beginners setting up their first Python projects, and anyone preparing for a Python interview
**Difficulty:** Easy
**Python version:** Example 1 was run on CPython 3.11 and in this page (Pyodide 0.25.1, CPython 3.11.3); Example 2 creates a real environment, so it was run on CPython 3.12 outside the browser. The shell output below is from python3.11 on Linux.

> **How to read this doc:** Each idea is explained in plain language first, then tagged with `📌 Interview term:` so

Question 2

What is the difference between a module and a package?

Accepted Answer

**Target Audience:** Beginners learning Python, and anyone preparing for a Python interview
**Difficulty:** Easy
**Python version:** Every example was run on CPython 3.11 (and in this page on Pyodide 0.25.1, which is CPython 3.11.3)

> **How to read this doc:** Each idea is explained in plain language first, then tagged with `📌 Interview term:` so you also learn the exact word an interviewer expects. Every output block in the **Verified** section was copied from a real run of the examples on th

Question 3

What is uv and why is it replacing pip/poetry in 2025-26?

Accepted Answer

**Target Audience:** Python developers who know pip and venv and keep hearing about uv, and candidates asked about modern Python tooling
**Difficulty:** Easy
**Python version:** The in-page examples were run on CPython 3.11 and in this page (Pyodide 0.25.1, CPython 3.11.3). The shell sessions were run with uv 0.11.32 on Linux against python3.11; uv changes quickly, so check `uv --version` and the docs for your release.

> **How to read this doc:** Each idea is explained in plain language first,

Question 4

How do uv workspaces and named dependency groups work?

Accepted Answer

**Target Audience:** Developers moving a multi-package Python repo to uv, and candidates asked about Python monorepos and modern packaging
**Difficulty:** Medium
**Python version:** The in-page examples were run on CPython 3.11 and in this page (Pyodide 0.25.1, CPython 3.11.3). Every uv session below was run with uv 0.11.32 on Linux against python3.11; long `file://` paths are shortened to `file://.../` and the timing in "Resolved N packages in Xms" lines will differ on your machine.

> **How to

Question 5

What are common Python security pitfalls?

Accepted Answer

**Target Audience:** Developers who write Python services or scripts and want a concrete checklist; no security background assumed.
**Difficulty:** Medium
**Python version:** Examples 1 and 2 were run on CPython 3.11 (python3.11 and the in-page Pyodide 0.25.1 runtime, CPython 3.11.3). Example 3 needs `sqlite3` and the `tarfile` filters, which the page runtime does not have, so it was run on python3.12 (and gave identical output on python3.13).

> **How to read this doc:** Each idea is explained

PYTHONDECODED.

Easy

Why use virtual environments?

What is the difference between a module and a package?

What is uv and why is it replacing pip/poetry in 2025-26?

Medium

How do uv workspaces and named dependency groups work?

What are common Python security pitfalls?