title: What does it mean to "run library module as a script" with the "-m" option?
body: <p>I'm new to Python (and to programming as well) and, although well documented, I cannot understand what exactly means the -m directive (precisely in the creation of a virtual environment: <code>python3 -m venv my_env</code>. </p>
  
  <p>As far as I can read from the documentation, it stands for "run library module as a script": it is in fact this concept that I cannot figure out and what is the difference in running the command without the <code>-m</code>.</p>
  
  <p>Moreover, it this a characteristic of Python 3?</p>