Minecraft’s 1.17 update was launched a few weeks ago, but it was only part of what is collectively called the Caves and Cliffs update. We’ve known what’s coming in at 1.18 for a while, and the key feature, new terrain generation, is now available for play via an experimental beta.
A post on the Minecraft website explains how to get on board. There are technical reasons why the snapshot cannot be rolled into the regular Java beta, and this is therefore marked as more explicitly experimental. Outside, the changes are exciting enough to make it tempting.
Since this is such a big change, the 1.18 beta will not be able to open worlds generated in earlier versions of the game. You have to start a new world fresh.
The same update is also available on Bedrock, which gets its own, similar post about the update and how to access it via version 1.17.10.
To learn more about Minecraft’s recent updates, check out Ollie’s almost endless guides. For example, he explained yesterday how to get bees in Minecraft.