Block

Blocks are the basic units of structure in Minecraft.

Behavior
Blocks are arranged in a grid, each cell of which is 1 cubic meter, and are snapped to it, which means a block cannot be in more than one cell. There might seem to be exceptions, such as beds and falling sand, however, a bed consists of two blocks, each making up one half of it, and when a block of sand falls it converts to an entity instead.

Together, solid, liquid and air blocks build up the in-game environment and can be harvested and utilized in various fashions. Some blocks, such as dirt and sandstone, are opaque, while other blocks, such as glass and ice, are transparent.

Some blocks, such as torches and glowstone, will emit light. The amount of light they emit varies widely; see this table of light values for further information. Opaque blocks completely block light, while transparent blocks either have no effect on light or merely weaken it.

Almost all blocks will ignore gravity, with the exception of sand, red sand, gravel, anvils, dragon eggs, concrete powder, scaffolding, and snow.

Mostly, only one block can occupy a single grid cell at a time. The only exceptions to this are snow layers, which can combine with each other up to eight in a cell, and water, which can combine with most non-full-size blocks using a game mechanic called waterlogging.

so i was chillin with my mates on the couch

and then billy said "ey mateys, let's play that blocky game called minecraft"

and i was disgusted with billy but my other mates said sure

so i just followed along

in miecraft we were were building a house with wool because why not

and then a guy we didn't know came and he had white eyes (im not racist tho)

and he was like "h-hewwo...owunce of weed pwease >///< arigato... dealer-kun puts weedie-chan in bong and inhales waaah!! (╯✧▽✧)╯ daisuki cannabis desu~! (^ ω ^ )uwaaa! weedie-chan i feel so kimochi!!(〃°ω°〃) hehe~ ur deep inside me now x3"

and he brought out a 26 year tall sword and murder us

and redstone went on the grass

and in real life our mom came and she was like "Uhm😤 by the way👩MOM 🙆They're not 🇨🇳 Chinese cartoons 📺💻it's called 😡ANIME!!!😍😍 GOT IT?!?! 😤😠 And they're ❌✋🙅NOT CHINESE!!! 🇨🇳 They're JAPANESE!!!!!!🇯🇵 🎌 So you'd better apologize 😱🙏🙇👎to me and my Waifu 👫💏RIGHT NOW 😡😠"

the end

Block height
Most solid blocks are 1 meter high, but certain blocks (especially slabs and stairs) have non-standard block heights.

A player can automatically step up from a lower to a higher height if the difference is at most 0.6 ($3/5$) of a block.

Textures
The textures on the faces of blocks are 16×16 pixels. Most blocks are proportionately one cubic meter by default, but their shape can be changed using models. Most blocks also have static textures, though water, lava, Nether portal, End portal, End gateway, fire, sea lantern, command block, prismarine, and magma blocks are animated.

Using resource packs, the player can change the textures and resolution of blocks, including whether their texture is animated. They can also change the shapes of blocks using models and the size of blocks to any size with equal width and height, though sizes that are a power of two tend to work better.

Natural blocks
Natural blocks are generated as part of the terrain in the Overworld, the Nether and the End. These also include ores and liquids. Some of these blocks are generated as part of structures.

Plants, animals and fungi
These blocks are Minecraft's representation of various life forms. Most of them can grow and be farmed to obtain resources.

Manufactured
Manufactured blocks can be obtained via crafting or smelting. Some of them can also be found in generated structures.

Utility
Utility blocks are used for a wide variety of specific purposes that are helpful to the player.

Mechanisms
Mechanisms can be used to perform a wide range of tasks.

Creative only
These blocks are only accessed within the Creative mode inventory.

Commands only
These blocks are only accessed with the use of commands, such as.

Bedrock Edition/New Nintendo 3DS Edition only
These blocks can only be accessed in Bedrock Edition and New Nintendo 3DS Edition. In these versions, item frames work as block entities, stonecutters are only obtainable from creative mode inventory, through commands, or by inventory editing, and glowing obsidian, Invisible bedrock and nether reactor cores are not obtainable at all but continue to exist in old worlds.

Education Edition (mobile) only
These blocks can only be accessed in Education Edition and Bedrock Edition

Removed blocks
Removed blocks no longer exist in current versions of the game.

Technical blocks
Technical blocks are blocks whose main functions are strictly tied to the usage of other blocks. They cannot be acquired through normal gameplay, most of them cannot be obtained with commands and even external editors, but other ones require commands or mods to obtain. They serve various purposes during events within the game. If acquired, they will usually have a missing texture.

Many of these blocks have different representations in the inventory; flint and steel is used to place fire, water and lava can be placed with their respective buckets, and blocks such as beds, doors, cake and flower pots have separate inventory items.

Trivia

 * Certain blocks may interpret positions they cannot be placed in by normal means as a valid position. For example, a sign placed in midair via or through  will remain in midair even when updated, until either it is broken, or a block is placed below it and broken.