This is when there is not enough room in the mouth for all the teeth to fit in alignment.
Crowding could be caused by a jaw/tooth-size discrepancy.
Crowded teeth can be unaesthetic and can cause uneven tooth wear. They are more difficult to clean which makes them more susceptible to decay.
Early treatment may help to make space for the adult teeth to come through more favourably while there are still some baby teeth left, which subsequently may avoid extractions later. This is why it is important for an orthodontist to see children while they are still growing and before they have lost all of their baby teeth.