A recessive allele is an allele that gets covered up by a dominant allele.
Example -
Lets say that two people were breeding. Brown hair would be the dominant trait, with blonde as a recessive. If the male has the allele Bb, and the female has bb, then you would put these into a table. Your outcome would come as
B b
b Bb bb
b Bb bb
So there would be a 50/50 chance of the offspring having brunette or blonde hair.
