How do I know which version of Debian I'm running?

In a tutorial, I'm prompted "If you are running Squeeze, follow these instructions..." and "If you are running Wheezy, follow these other instructions..."

When I run uname, I get the following information:

Linux dragon-debian 3.2.0-4-686-pae #1 SMP Debian 3.2.63-2+deb7u2 i686 GNU/Linux

Is that information enough to know if I'm using Squeeze or Wheezy, or do I get that from somewhere else?