Block

Minecraft is composed of and built entirely out of blocks. They are the basic unit of Minecraft. You dig through blocks, you build with blocks, your character is made of blocks; they are everywhere. It is possible to change how the blocks appear by applying new Texture Packs.

The face of a block is 16x16 pixels, and each block is proportionately one cubic meter. Water, Lava and Portal blocks have a shifting pattern for each face.

Types of Blocks
There are currently 76 different types of blocks (including Air, still Water, still Lava, blocks which cannot be built at the  moment, (see data values for the full list).

In a standard randomly generated Beta Map you can find the blocks Stone, Grass (or Snow), Dirt, Water, Lava, Sand, sandstone, Gravel, Gold ore, Iron ore, Diamond, Redstone, Lapis Lazuli ore, Clay, Coal, Ice, Tree, Leaves, Cactus, Sugar Cane, yellow and red Flowers and brown and red Mushrooms. In dungeons (added in Seecret Friday Update 2), you can also find Cobblestone, Moss Stone, a Mob Spawner, and Chests, even though cobblestone and chests are usually made by the player. Obsidian can be found naturally, but it is not part of the random generation, instead it is created when naturally occurring lava source blocks and water come in contact. Cobblestone can also be found naturally, and is formed with the same circumstances as obsidian, except that it is formed when water and moving lava contact.

In the initial free version of Survival the player began with 10 TNT blocks and could obtain Dirt, Cobblestone from Stone, Wooden Planks from Trees, Gold from Gold ore, Iron from Iron ore, Step from Coal, and white Cloth  from Sheep.

In Classic mode the player can build with naturally occurring blocks, save Redstone and Diamond, and can use Bookcase, Sponge, Coloured Wool, Brick, Obsidian and Moss Stone. Operators of servers can also build Bedrock. Some custom servers give the ability to place Grass and (still) Fluids, too.

When playing the current Beta, the player can craft a variety of blocks not naturally found in maps, including Stairs, Workbenches, Paintings, Bookshelves, Furnaces and more. Redstone, Diamond and Lapis Lazuli can be found in the lower areas of maps, and Obsidian forms when water touches a spring lava block. The Mob Spawner block may naturally occur in a Dungeon. Pumpkins can grow on the surface.

The blocks Netherrack, Glowstone, and Soul Sand can be found in The Nether, which the player can only enter by creating Portal blocks.