Empty buckets can be used to collect water and lava and store them somewhere else. Getting a water bucket and creating an infinite water source is the first thing an experianced player does when they get a bucket; as water can be found everywhere. Lava buckets are most commonly gottom by finding lava lakes, but what most players forget is that whereever there is water in the overworld, there is lava in the nether. Milk is used to make cake or to cure potion effects instantly.
Note: N stands for Nothing, II stands for Iron Ingot.
In a crafting table; Top Row: N,N,N. Middle Row: II,N,II. Bottom Row: N,II,N.
Water Bucket - can hold a water block
Lava Bucket - can hold a lava block
Milk Bucket - can hold milk to make cake or to cure potion effects