Glossary

Concise definitions of common Minecraft world-file terms. Tap any entry for the full explanation.

.mcpack / .mcaddon

.mcpack is a single resource pack or behavior pack, .mcaddon is an add-on bundle that packs several packs together, and .mctemplate is a world template (a preset used when creating a new world) — they are all ZIP-style files for Bedrock, but none of them is a complete world, which is what sets them apart from .mcworld, which holds an entire save.

.mctemplate

.mcworld is one specific Bedrock world (the exact save you jump straight into after importing). .mctemplate is a "world template": every time you create a new world from it, the game generates a separate copy while the template itself stays unchanged. Under the hood both are just ZIP archives with a renamed extension and a very similar structure.

.mcworld

.mcworld is the packaged file Minecraft Bedrock uses to share and import worlds. It's essentially a world save (including level.dat, db/, etc.) compressed and renamed with a .mcworld extension instead of ZIP. Open it on a device that has Bedrock installed and the world is imported into the game.

Behavior Pack / Resource Pack

A resource pack only changes a world's "looks"—block textures, sounds, models, and UI. A behavior pack changes the "logic"—entity behavior, drops, crafting, game rules, and more. Both are Bedrock mechanics, stored separately from the world save, and must be enabled in-game individually.

chunk

A chunk is the basic unit Minecraft slices the world into: 16×16 blocks wide and spanning the full world height. World data is stored and loaded per chunk: wherever you walk, the game generates and saves the nearby chunks. When TopoBlocks opens a world, it runs a structure check (file type, version, structure, missing files), and the more chunks you explore, the larger the world file becomes.

dimension

A single Minecraft world packs all three dimensions—Overworld, Nether, and End—into one save. Java Edition keeps them in separate folders like region/, DIM-1/, and DIM1/ (.mca chunk files), while Bedrock stores them all together in db/ (LevelDB), telling them apart by an internal dimension identifier. They share the same level.dat metadata.

game rules (gamerules)

Game mode, difficulty, and game rules are all world-level settings, stored together in the level.dat file at the root of the world save and recorded in NBT (binary tag) format. Opening level.dat lets you read this metadata, but you need a dedicated tool to parse it — Notepad won't show it in a readable form.

level.dat

level.dat is the core metadata file found in the root folder of every Minecraft world save. Stored in the binary NBT format, it records information such as the world name, game mode, random seed, spawn point coordinates, and game rules. The game relies on it to identify and load the world, so if it's missing or not in the root folder, the world often won't import or open.

level.dat_old

level.dat_old is the previous automatic backup of level.dat: each time the game successfully saves a world, it keeps the old level.dat as level.dat_old. It can serve as a fallback clue when level.dat is corrupted, but it is only the world's metadata file, not a full world backup — the actual block and chunk data lives in db/, not in these two files.

LevelDB (db/)

The db folder inside a Bedrock world save is a LevelDB key-value database that holds the real world content—chunks, blocks, entities, containers, and more. level.dat only records metadata, while db is the world itself, so once it gets corrupted you may end up with missing chunks or a world that won't open.

NBT

NBT (Named Binary Tag) is the binary format Minecraft uses to store world metadata, entities, block entities, and more—files like level.dat and player.dat are NBT inside. Because it's binary, opening it in a plain text editor shows garbage; you need an NBT editor or the game itself to read it.

region/.mca

region/.mca files are where Java Edition stores a world's chunk data: the game slices the world into 32x32-chunk regions and saves each region as a region/r.x.z.mca file, in NBT binary format. This differs from Bedrock's db/ (LevelDB), so the two editions' worlds can't be imported into each other directly.

seed

A seed is a string of numbers that Minecraft uses as a random starting point to generate a vanilla world's terrain, caves, villages, and biomes—the same seed plus the same version produces a nearly identical map. It's stored in the world's level.dat. Note: a world built from real map data is a different thing from random-seed terrain. The former reconstructs real buildings/roads/elevation and does not rely on a seed.

TopoBlocks

TopoBlocks is an independent iOS app for creating, checking, repairing, converting, backing up and hosting Minecraft worlds. It works with .mcworld files, Java world ZIPs and server workflows, but it is not the .mcworld file format itself and it is not an official Minecraft product.

world save

A Minecraft Bedrock world save is a folder containing level.dat (world metadata), the db/ LevelDB database (chunk and block data), levelname.txt, and other files; its physical location varies by platform. On iOS it sits inside the app sandbox, so you have to export or share the world as a .mcworld file before you can take it out and inspect it.

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