An agreeable succession of sounds; sweetness of sound; the particular air or tune of a musical piece.For a sample melody, click here.
Rhythm is defined as:
Periodic emphasis in verse or music; metrical movement.For a sample guitar rhythm, click here.
Tempo is defined as:
The time of a piece of music.Tempo can be fast, medium, or slow.
Melody along with with rhythm and tempo combine to make music.
Melody is the tune of a song, the part that you sing, whistle, or hum. The melody itself can be very rhtyhmic, punctuated by alternating periods of silence and musical notes.
Melody takes many forms in music from the singer's part to the jazz saxophonist's solo to the rock guitarist's lead.
Rhythm creates a framework for the melody. Therefore, the purpose of rhythm is to support the melody. The rhythm can be carried by a guitarist, pianist, bassist, horn section, and just about any other instrument you can think of. Of course, some instruments are better suited to rhythm than others.
In the guitar world, rhythm is performed by - who else? - the rhythm guitarist. Some rhythm guitarists play very melodically. This can be seen in many jazz recordings as well as rock. One of the best rock rhythm guitarists is Keith Richards of the Rolling Stones. In a recent jam session with Keith Richards, Chuck Berry told Richards "Man, you play some pretty chords.".
Chords are simply three or more musical notes played simultaneously as in a strum or pluck of guitar strings.
It is my belief that the first thing a guitarist should concentrate on is how to play rhythm. A good rhythm guitarist is a 100 times more useful than a guitar player that can only play leads. And, yes, there are some guitarists who play solid solos but are very weak rhythmically.
An example of rhythm follows:
Tap one foot, one time per second. Each time the front part of your foot hits the floor, you have just ended one beat. The time between foot taps is where rhythm comes into play. That time between foot taps can be divided into halves, fourths, and eighths. Think of tapping your other foot four times per second and you start to get a feel for rhythm.Add in periodic rests (short periods of silence) to break up the rhythm even more. Vary the time between beats from halves to fourths and the rhythm sounds even better.
A metronome is a good tool for helping you "stay in time" by clicking out the beat count (one beat per second, 2 beats per second, etc.)