Why do babies suck on bibs?

They could be teething, but they do have suck on things just for comfort too. They have a natural sucking reflex (a natural thing since nature intended their first meals come from the breast). Babies often can be seen sucking on their thumbs and fingers in the womb. Babies in the early stages also explore with their mouths so they stick just about everything in their mouth when they are young. This is just their way of exploring the world.