Why Dependencies Need Isolation
beginner10 min readLesson 41 of 169
Version conflicts, and the venv pattern that fixes them.
Your first projects used only the standard library — nothing to install. Real projects lean on third-party packages (requests, rich, pytest...), and that creates a problem: two projects on one machine often need different versions of the same package.
The problem
project-a needs requests==2.25
project-b needs requests==2.31
Install globally and one project silently breaks the other.
The fix: virtual environments
A venv is a private, disposable Python setup for one project:
python3 -m venv .venv # create (once per project)
source .venv/bin/activate # activate (every shell) — Windows: .venv\Scripts\activate
With the venv active, pip install affects ONLY that project. Deactivate with
deactivate. The venv is regenerable — delete it, recreate it, nothing of
yours is lost.