Here is a quick, but very cool overview of equalization (EQ). The video (from the WinkSound YouTube Channel) shows you different kinds of EQ and goes over the parameters of each. It also goes over what controls are typically available (bandwidth - sometimes called "Q," frequency, amplitude, etc.) on different types of EQ units or plugins.
By the way, there are built-in EQ tools in both Audacity and Reaper recording programs, and we show you how to use them in both of our courses in the Newbies Guide To Audio Recording Awesomeness series (TNGTARA 1 uses Audacity and TNGTARA2 uses Reaper).
And without further ado, here is the video: