Installing drush

Drush is a great command line tool, but how do you get it on your computer?
What are the parts to the installation?
How do I use it, or know if it's available for use?

We will go over these using a mac, and try to answer any questions you may have, during this BoF, which is a follow up to the session:

Schedule Information
Time slot: 
Wednesday · 13:00-14:00