why we create virtualenv in python code example

Example 1: create a virtualenv python

pip install virtualenv
cd projectfolder #go to project folder
virtualenv projectname #create the folder projectname 
source projectname/bin/activate

Example 2: setting p a virtual envioronment

#Creating a Virtual Environment | Windows 10
#Proceed to the folder were you want to create your environment, Then enter the following:
...\> py -m venv project_name
#To activate the environment, run:
...\> project_name\Scripts\activate.bat
#Then install Django using pip
...\> py -m pip install Django