Chords. Root notes and bass notes

Lets review these important terms. 

Beat      The steady pulse of music that we respond to when we tap our feet, nod our head, tap with our hands etc...

Tempo   Speed of the beat.  This is measured in Beats Per Minute or bpm

Note  A musical sound.  On guitar we play single notes on individual strings.

Pitch      The relative highness or lowness of a note

Chord   Three or more notes sounded (played) at the same time.

What is a root note?  I am going to quote from studybass.com

"A root note is the main note on which a chord is built. It is the foundation, or root, of the chord. For example, the three notes G, B, and D form a G major chord. The note G is the chord's root note.

In music theory, the bass note of a chord is the lowest note played or notated. While the bass note is often the root of the chord, it does not have to be, and sometimes one of the other pitches of the chord will be found in the bass. See: chord inversion (music).