Want to understand what's going on with linux command
===

I am installing a virtualenv and want to understand what's going on.

$ curl -O https://raw.github.com/pypa/virtualenv/master/virtualenv.py
- I understand curl fine

$ python virtualenv.py my_new_env
- Understand this, too

$ . my_new_env/bin/activate
- Here's where I get lost.  What is the period doing here?

(my_new_env)$ pip install ...
- What does it mean to have the parentheses here?  Does this use tell me I'm in a folder?