By Flask Team
Use a virtual environment to manage the dependencies for your project, both in development and in production.
What problem does a virtual environment solve? The more Python projects you have, the more likely it is that you need to work with different versions of Python libraries, or even Python itself. Newer versions of libraries for one project can break compatibility in another project.
Virtual environments are independent groups of Python libraries, one for each project. Packages installed for one project will not affect other projects or the operating system’s packages.
Python comes bundled with the venv module to create virtual environments.
# macOS/Linux
$ mkdir myproject
$ cd myproject
$ python3 -m venv venv
# Windows
> mkdir myproject
> cd myproject
> py -3 -m venv venv
Activate the environment
# macOS/Linux
$ source venv/bin/activate
# Windows
> venv\Scripts\activate
Your shell prompt will change to show the name of the activated environment.
Install Flask
$ pip install Flask