Snowball

Snowball is an item that was added during the Minecraft Alpha 1.0.5 update. They are obtained when a snow block (4 snowballs obtained) or snow (1 snowball obtained) is destroyed with a shovel (as of the 1.0.5_1 update). They can be stacked up to 16 snowballs. They are a throw-able item that does not do any damage. Although it does not do any damage it still knocks back creatures and gives the same effect as if it was damaged. This makes it useful for herding and useful for knocking creepers off of high areas. Hitting sheep will even sheer the sheep making it an effective way to get wool without hurting the sheep. Snow balls cannot be placed, they can only be thrown. Snowballs can be combined to make a snow block.

Trivia:

Before the Seecret Saturday Update 1, you could get more than 4 snowballs from each block