When absolutely everything in the world is new and exciting for a newborn, a simple ball is an amazing thing. It can be picked up, dropped, sat upon, thrown, bounced, corralled and (last but certainly not least in the long list of amazing ball qualities) rolled.
All of these tasks aid in infant development. While we take for granted our brains' ability to know where a ball will go when rolled, it's a concept that takes time to master. It teaches the use of force as babies experiment with varying degrees of effort when they push a ball across the floor and then watch the results in the distance.
Retrieving a ball helps develop spatial awareness as babies learn to match their visual targeting with the length of the journey. The other thing about a ball: In addition to being a boon to infant development, it's a heckuva lot of fun.
Keep reading for lots more information on toys for infant development.