The Phoneme is the smallest unit of a language that can change meaning.
Phonology is the study of sounds (phons) that humans can make for oral communication. Humans are capable of a great many of these sounds.
The hurdle that the baby has in learning language is that each language has its own personal selection of sounds to serve as individual units.
We call them collectively phonemes. The child must learn what those units are for his/her language.
The phoneme is the smallest unit of a language that can change meaning.
Hence, when I go to the doctor after a fight with my wife, I may report that she either bit me or beat me.
In English, the "i" (as in "bit" ) and "ee" (as in "beat") sounds make a difference in meaning, so they are phonemes.
In Russian, those two sounds are not distinguished as seperate, so that my Russian friend may say his wife beat him when there are clearly teeth marks in his arm.
NOTES: See a discussion in deph on Phonemes
NOTES: Get more information on Phonemes
NOTES: Here is a tutorial on Phonemes.