what does creating a virtual environment python mean code example

Example 1: virtual env create python

#------FOR LINUX/MAC---------#
#installing venv 
sudo apt-get install python3.6-venv
#creating virtual env
python3 -m venv env
#activating virtual env
source env/bin/activate


#-------FOR WINDOWS----------#
#installing venv
py -m pip install --user virtualenv
#creating virtual env
py -m venv env
#activating virtual env
.\env\Scripts\activate

Example 2: create a virtualenv python

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

Example 3: how to use virtual environment python

python3 -m venv env

Example 4: create virtual environment python

python3 -m venv tutorial-env