Babies begin babbling around two months of age, and most parents—if they're not too exhausted—are able to distinguish the difference between cries of hunger, pain, and pleasure. (Check out what first babbles sound like.)
By about six months, babies are usually quite pleased with the sounds they can make (not to mention the amount of saliva they can produce while making them). They can repeat single syllables and begin listening more intently to those around them.
By one year, most babies can follow simple instructions and should recognize their names when called. At this age, children are usually able to recognize and say a couple words, such as "mama" and "dada." Some children may also be able to formulate additional words, such as "yes," "no," "more," "eat," or "bye-bye."