What does it mean when a child has to have a lot of attention?

Normal finding: Infants and young children are the center of their own world & expect those in their environment to provide them with attention, praise and nurturing.I find it unusual and worrisome if a small child does not.By school age, they are introduced to others with a similar self interest & sometimes tone it down a bit to get along.Failure to receive attention invalidates the child & engenders worthlessness.