Minecraft uses a special algorithm to generate massive, seemingly random worlds. The Minecraft world generator does this by randomly assigning values, which are known as Minecraft seed codes, or simply Minecraft seeds. A seed of a randomly generated world can be viewed by typing the command /seed. Once you have the Minecraft seed codes for some specific worlds, it is possible to revisit one of those worlds at any time.
These Minecraft seed codes that are assigned automatically by the Minecraft world generator are produced according to system time, or your computer’s notion of time. Beyond these automatically generated Minecraft seeds, it is possible to input your own Minecraft seed codes for unique results. With such Minecraft seeds, it is possible to generate a theoretical 4 billion different worlds if only words are used. However, if numbers are also used in the Minecraft seed code, the Minecraft world generator can produce a staggering 281 trillion different worlds. This difference is due to the fact that the Minecraft world generator only recognizes 4 billion words, and thus will only create Minecraft seed codes for these words.
It is important to note that any Minecraft seeds that are manually input into the Minecraft world generator is ran through an algorithm, and therefore entering the same seed at a later date may not result in an identical world. The Minecraft world generator updates periodically, and along with this update, the Minecraft seeds algorithm is changed.
It is also important to note that there is no direct correlation between the words used and the world that is generated. For example, using the seeds “desert” or “forest” will not create a map that contains primarily those biomes. This is, once again, due to the algorithm used by the Minecraft world generator and the fact that, while there is a list of words that are acceptable as seeds, these words have no definitions or requirements attached to them.
Finally, regarding saved worlds, it is possible for a saved seed to change if the algorithm is updated. This can cause “chunks”, or 16×16 parts of the map, to either change or get deleted. This is especially noticeable in multiplayer, in which several players may be using different versions of the software. This can be problematic for someone who likes to save their seeds, but usually the changes are not drastic, and any lost structures can be repaired.
Seed generation is a complicated process, and one that is widely misunderstood, but it essentially breaks down as follows: The world generator either generates a world based on system time or based on manual input. These manual seeds are run through an algorithm that decides the world, and if the algorithm changes, the world generated changes. Keeping these rules in mind, it becomes easier to understand the process of world generation in Minecraft.