Stone

Stone, also known as Smooth Stone, is a block found underground everywhere in the overworld. If mined with any pickaxe without the Silk Touch enchantment, it will drop cobblestone. Stone is often used in building because of it's smooth texture.

Smelting
Stone can be obtained from smelting cobblestone in a furnace

Mining
Stone is generated under 2-4 layers of grass and dirt on the ground in the overworld, and goes all the way down to bedrock, making approximately 60 levels of stone.

Lava and Water
Stone is made when lava flows on top of water, but if water flows onto lava, it will turn into cobblestone.

As a crafting ingredient
= 1 Stone Button = 1 Stone Pressure Plate = 3 Stone Slabs = 1 Stone Brick = 1 Redstone Repeater