Virtual environments are not optional — here's why

Installing packages globally feels faster — until two projects need different versions of the same library and your environment becomes a minefield.

What a venv buys you

• Isolated dependencies per project, so upgrades never spill over.
• A clean list to freeze into requirements.txt or a lock file.
• Reproducible setups for teammates and CI.

It takes two commands

python -m venv .venv
source .venv/bin/activate   # Windows: .venv\Scripts\activate

Whether you use the built-in venv or a faster manager, the habit is the same: one environment per project, every time.