My son is 18mth+. He's not really talking yet. Understands what we say, but still using mostly his own language. So far, he can say 'bye bye', 'bird', 'six', 'muak!'... that's about it I think. But he sings to himself when he's happy. Can roughly make out that it's ABC or twinkle twinkle little star. He points at what he wants and shakes his head when he doesn't want something. He's very active and will climb up anything: sofa, chair, table, etc. When happy, he sometimes walks in circles or 'dances' to himslef. Whenever he can, he'll shread tissue, and remove the batteries from the TV remote control. When he's in a bad mood, he'll throw his toys everywhere; when he's in a good mood, he'll put his toys back in their proper containers and places. If he thinks that you're going out, he'll run ahead of you to the door and park himself there so that you would take him with you. Oh yes, and he also covers his own eyes to play peek-a-boo with you. But after a few rounds, he'll peek out from between his fingers to see if you're still looking at him.