home.md

@@ -1901,4 +1901,45 @@ As you can see from the example above, the Python package(s) will be installed i
 
 **Location: /home/username/.local/lib/python3.6/site-packages**
 
+### Python virtual environments
+If you are working on different projects and you need different Python packages for each project, it is better to work in a special virtual environment.
 
+When you activate this virtual environment, it will create a special virtual Python environment for you.
+In this virtual environment you can use the **pip** command (without the --user option) and other command.
+
+You create a new virtual environment with the command:
+* $ virtualenv envname
+
+You activate a new virtual environment with the command:
+* $ source envname/bin/activate
+
+You deactivate a virtual environment with the command (it will not be destroyed):
+* (envname) $ deactivate
+
+Example:
+```
+virtualenv Project-A
+Using base prefix '/usr'
+New python executable in /home/username/Project-A/bin/python3.6
+Also creating executable in /home/username/Project-A/bin/python
+Installing setuptools, pip, wheel...done.
+
+
+[username@res-hpc-lo01 ~]$ source Project-A/bin/activate
+(Project-A) [username@res-hpc-lo01 ~]$ 
+
+(Project-A) [username@res-hpc-lo01 ~]$ deactivate 
+[username@res-hpc-lo01 ~]$ 
+
+
+(Project-A) [username@res-hpc-lo01 python3.6]$ pip3 list
+Package    Version
+---------- -------
+pip        20.1.1
+setuptools 49.1.0
+wheel      0.34.2
+
+
+(Project-A) [username@res-hpc-lo01 ~]$ deactivate 
+[username@res-hpc-lo01 ~]$ 
+```