Minecraft users love that you can get a random world each time you make a new one. The technology behind this is called terrain generation, a special code that dictates how a Minecraft world is made.
Minecraft worlds are not “truly” random; you can always generate the same world each time you play. Welcome to the concept of seeds, the core of Minecraft world generation. Whenever computer scientists want a computer to generate something randomly, they can’t just say “Okay PC, do something random, please.” Instead, they set up an algorithm that takes in a number and uses it to generate something else.
For example, you could make a computer program where if you enter one number, it spits out a different one. To do this, you make the algorithm “(x*10)+5” and have the user input represent X. So, if someone types in “1”, it spits out “15.” If they enter “2”, it spits out “25”, and so on. In this algorithm, the ‘X’ is the seed. Changing the value of X changes the result, and keeping it the same gets the same result each time.
Welcome to My World
Minecraft does this on a more complex level. Its algorithm calculates a whole world, from dizzyingly high mountains to the depths of the earth. While it’s amazing that Minecraft can do this with a single number, it also means that if you enter the same number between two world generations, you’ll get the same terrain on both.
To do this, open up Minecraft, click “Single Player,” then “Create New World,” then the “World” tab. Here, you can enter a seed for the world generator. Feel free to type in any number you like, but don’t be afraid to use letters; Minecraft can convert those into numbers for use in the seed. If you leave the field blank, Minecraft will randomly select a number and feed it into the
algorithm. This is why you can generate a world without typing in a seed every time.
If you make two worlds using the same seed, they will have identical terrain. Stuff like mob spawning is done in real-time, so that won’t be the same. However, the terrain algorithm (the bit that depends on the seed you entered) will be the same. When we made a world with the seed ‘A’ in Minecraft 1.20.2, we started on top of a tree in a sprawling jungle. Use the same seed (using a capital A) and see for yourself.
Fortunately, Minecraft worlds that have already been generated “remember” the seed that made them. Just load up the world you want to copy and type ‘/seed’ in the chat to get the number. Now you can generate that same world whenever you like. If someone gets lucky enough with their world generation, they can grab the seed and share it online. As such, you’ll find plenty of seeds for your next world out there, from pretty biome generations to important structures generating right next to spawn.
Just be sure that your version of Minecraft matches the version the other person used when they generated the seed. Nothing bad will happen if there is a mismatch, but given how the world generation algorithm has changed over time, the same seed used on different versions of the game may act differently.