Between the age of 0-3 years infants start to interact with their friends/family. They start to smile and start to try and respond when adults talk. Infants start to become shy as they grow and also, they tend to become scared of strangers because they could start telling the difference between familiar and unfamiliar people. At around 2 years old they will get interested in playing with other children but not exactly interact with them. As they grow older they learn how to share their toys with others to start making friends and also they would be able to stay away from their parents for a few hours.