Definitions of stuff: Layers/Levels - A level of 1 layer of blocks. Each block is on a level or layer. Grass Block - Dirt, but with grass growing on it. In some biomes, you can find flowers or trees growing on it. Found anywhere where there is dirt and enough light. Dirt - Just common dirt. Found almost anywhere. Stone - The most common material. Found almost any where, just not typically above level 100 Coal ore - Spawns commonly around and below level 40, can be found up to about level 60. Drops coal when mined with any type of pickaxe. Iron ore - Found in large quantities around and below level 40, can be found up to roughly level 50. Drops iron ore when mined with any type of pickaxe above wood, turns into iron ingots when smelted. Gold ore - Does not generate higher than level 30. When mined with an iron pickaxe or better, (Gold ore surprisingly, cannot be mined with a gold pickaxe, as all other ores can be mined with a pickaxe made of their material.) When smelted, it yields 1 gold ingot per block of ore, Lapis lazuli ore - Not generated above level 30, very common around the levels 12 and 16. Drops multiple lapis lazuli when mined with a stone pickaxe of better. Emerald ore - Not found higher than level 30, generates in 1 block veins, and only in the Extreme hills biome. Can only be mined with an iron pic or better. Pretty useless, can only be used in emerald blocks and to trade with villagers. Redstone ore - Never generates above level 16, spawns in large veins around level 12. Each block of redstone ore drops up to 6 redstone dust, if mined with an unenchanted iron pic or better. Diamond ore - This is supposedly the most coveted ore in the game, and when mined with an iron pickaxe or better, it drops 1 diamond. It only generates below level 16, in small veins. The veins consist of about 2-6 diamond ore. Bedrock - This block is at the bottom on the minecraft world, and it is indestructible on survival mode. (You can destroy it on creative mode on some platforms) Bedrock hides the endless void beneath the world, which kills you if you fall into it. It generates at layers 1-4, creating an uneven layer of blocks.
About the game Minecraft - Minecraft was developed by 'Notch' and 'Jeb' (Markus Persson and Jens Bergensten). It is a sandbox game, based on the principle of digging up and placing blocks. The graphics are made of large pixels, and everything is blocky and pixelated. You can visit the official website at: https://minecraft.net