Despite the fun of mining, mods, and monsters, the best part of Minecraft is the limitless array of surreal, randomly-generated worlds to play in. Amazingly, all those labyrinthine caverns, hanging cliffs, and floating islands start with short strings of numbers called map seeds.
Minecraft seeds are the start of a highly complex mathematical formula that creates a world from scratch. All the cliffs, valleys, lakes and caverns you see are the result of an algorithm that extrapolates the seed, leaving no two worlds exactly alike. The world generator draws all-new terrain from the seed as you explore outward from the spawn point; the rest of the Minecraft world doesn’t exist in the map file before you see it for the first time. This is why the file size increases as you explore.
Minecraft world seeds are almost totally random. When you create a new map in Minecraft, you have the option of manually setting a seed and spawn point. This is where players can input a seed they’ve found on the forum or discussion boards; the world generator recognizes either a word or phrase like “Glacier” or a short string of numbers. If the seed generator is left blank, Minecraft uses the computer clock’s date and time as a random seed-another reason why it’s almost impossible to land in a world someone else has played before.
Okay, so the world possibilities are not exactly infinite. But starting from a random seed will give you access to 18 quintillion possible worlds.
But how can you be sure you’re playing a world where no man has gone before? Have no fear; as even if you use a seed posted by another user, no two worlds are ever generated in exactly the same way. Using someone else’s seed or a word or phrase input will generate a world with similar land formations on similar X – Y – Z coordinates, but because of the mathematical extrapolation involved, the world will never be exactly the same. From my own personal experience, if you play on two maps with the same seed, you will get eerily familiar blocks that aren’t quite exactly where you left them and a creepy sense of déjà vu. And if you don’t want to play on someone else’s world, never fear. Minecraft world seeds make sure every map is unique. That is, 18 quintillion kinds of unique – Good luck exploring them all!