Whole notes are 4 beats, half notes are 2 beats (half as long as a whole note), quarter notes are 1 beat (half as long as a half note), 8th notes are 1/2 beat (half as long as a quarter) and 16th notes are 1/4 beat (half as long as an 1/8 note).

 

For information about dotted rhythms, see this page.