The toddler brain is twice as active as the adult brain.
The structures of the brain that are sensitive to language and social-emotional response develop. Motor development continues at a rapid pace. Children explore the world around them in a much more interactive way than they did last birthday. 

Children this age often try to get hold of anything they haven't seen before; whether Mom's makeup or Dad's tools, they want to examine it. Any toy which encourages active play makes a great gift for a two-year-old, as are toys that stimulate a toddler's mind such as puzzles and musical instruments.