Chunks in Minecraft are the basic units of the world. They are 16x16x256 blocks in size and are generated procedurally when a new world is created or when new areas are explored. Chunks can be viewed by pressing the F3 key, which will open the debug screen. The chunk coordinates will be displayed in the top left corner of the screen, and the chunk grid will be visible as a grid of lines.
Viewing chunks can be helpful for a number of reasons. It can help you to understand how the world is generated, and it can also help you to find specific biomes or structures. Additionally, viewing chunks can be useful for troubleshooting performance issues, as it can help you to identify which chunks are causing problems.