my son will complete 4yrs next week. he is the only child. whenever he plays at home...he is talking to another 'imaginative' child and having a good talkative conversation. do i need to be concerned?

My little brother used to have conversations with his "friend" who apparently lived in the storage room at our childhood home, when he was 3 years old. It used to freak out my late grandmother so much because she attached the idea of the supernatural to my brother's imaginary friend haha. He stopped a little after his 4th birthday and I suspect it had to do with the fact that he started pre-kindergarten and started having real friends. Talking and playing with an imaginary friend is not that different from playing with action figures or dolls. Children at that age are very imaginative and it is completely normal to have imaginary friends. In fact, studies have shown that children with imaginary friends turn out to be more cooperative, creative, independent, and happy than those without. I'd say, just go with it but do not overindulge your child's fantasies too much. He will outgrow his friend as he grows older :)