When we're working on a project, we usually like the parts of the project that aren't our own code to stay the same. We might have a good reason to install a new version of Python or updated library on our system, but we don't really want those things to change within our development environment. Even more so, we can easily find ourselves targeting entirely different and incompatible system configurations with different projects. We need a way to set aside an area for each project that is separate and can be configured for the specific needs of that project. That's what we call a virtual environment.
The venv tool that's built in to Python 3.3, and later, creates a virtual environment for us. Each virtual environment created by venv knows which version of Python it should be using and has its own package...