1.5 years - 2 years old
This period of time brings on huge leaps and bounds in baby's development into a toddler. He will go from taking tentative steps holding your hand to charging around at full speed, mindless of all obstacles and perils in the way. His speech will come on from a few babbled words to a vocabulary of anything up to 50 words, and the ability to ask specifically for food or drink, rather than just crying when he needs something and can't express what that something is.
Their preference for one hand over the other will also probably make itself known. Nine out of ten humans are right-handed, but there's nothing wrong with left-handedness!
Between 18 and 24 months, their emotional and intellectual states will really change. They'll develop their tantrum skills, become frustrated at little things, and throw things in anger. They'll also have their feelings hurt more easily as time goes on, and become more sensitive to your moods and feelings, too.