Bones are an item primarily obtained by killing skeletons, strays, and wither skeletons, looting dungeon chests, or fishing as junk loot. They can also be crafted into bone meal for farming and dye production.
Bones are mainly used to tame wolves, as feeding a wolf bones has a random chance to turn it into a loyal pet.
Additionally, bones are used in composters, and the bone meal they craft into speeds up crop, tree, and plant growth. Due to their multiple uses in taming, farming, and crafting, bones are a highly useful item in Minecraft.