Dirt

"I don't really need to tell you where to find dirt, because you'll generally acquire stacks and stacks of it during the course of normal play. To stop it filling up your chests, consider using it to fill in terrain, rather than dig it out, when you want to flatten an area. Or make a farm out of it - growing anything from saplings to beetroot. Or just use it to convert the dirt shack you built to protect you from zombies on the first night into an enormous dirt palace with all mod cons."

- Duncan Geere

Dirt is a block found abundantly in most biomes under a layer of grass blocks at the top of the Overworld.

Natural generation
Dirt is found at any altitude, and comprises the majority of the upper terrain layers in most overworld biomes, bridging the gap between stone and grass blocks in various thicknesses.

There are approximately 1,850 dirt blocks per chunk in plains, forest, snowy tundra, jungle, and mountains biomes. There can be as many as 3,000 in chunks with high mountains. Dirt also generates naturally in some houses in villages. Dirt also generates as part of the dirt floor found in the starting point area in mineshafts.

Mineral veins
Dirt can generate in the Overworld in the form of mineral veins. Dirt attempts to generate 10 times per chunk in veins of size 33, from altitudes 0 to 256, in all biomes.

Post-generation
Farmland turns into dirt if either a mob jumps on it, or if nothing is planted on it and it is not within four blocks of water.

Coarse dirt can be tilled with a hoe to become dirt.

Certain blocks also transform into dirt when in invalid states, such as the death of grass blocks.

Obtaining
Dirt drops as an item when broken with any tool or by hand, but a shovel is the fastest way to break it.

Dirt based blocks
When grass, grass path, farmland, mycelium, or podzol is broken using a tool that is not enchanted with Silk Touch, it drops dirt. Grass path and farmland also drops dirt when broken with a Silk Touch tool, except for grass path in Bedrock Edition.

Farmland drops dirt when broken.

Usage
Dirt's primary use is for farming, but it can also be used as a highly available building block.

Farming
Dirt has the ability to grow saplings, sugar cane, mushrooms, sweet berries and bamboo, which can be planted directly in dirt under appropriate conditions.

Using a hoe on dirt turns it into farmland, enabling wheat seeds, pumpkin seeds, melon seeds, potatoes, carrots and beetroot seeds to be planted on it.

Grass and mycelium spreading
When a dirt block is adjacent to a grass block and is exposed to a light level of at least 4, it is eventually converted into a grass block at random intervals.

Mycelium spreads in similar fashion, but requires a light level of at least 9.

Sounds
Java Edition:

Block data
In Bedrock Edition, dirt uses the following data values:

Block states
In Bedrock Edition, dirt uses the following block states: