World seed

The world seed (or simply seed; referred to as seed for the world generator in-game) is a value made up of character(s) (including negative or positive integers) that is used as the basis for generating every Minecraft world.[1]

Seeds are somewhat compatible between Java and Bedrock Edition, with terrain generation and biomes being the same. However, the placement of generated structures differs between these editions.

Whenever the game has to generate a new world, it calls upon an algorithm known as Perlin noise. This algorithm outputs a pseudo-random value that is then used to determine the characteristics and features of the world. However, the algorithm always outputs the same value each time for a constant starting point (seed). Thus, the same seed generates the same terrain every time.