Z-level
Z-Level refers to the various maps with set borders that contain the playable areas of SS13. Moving off the edge of a z-level in space will take you to one of 3 z-levels at random (including possibly looping back to the one you just left). Certain z-levels contain interesting items and gear for the adventurous space explorer.
Station
This is the level that all crewmembers except miners start on. It contains the main space station, the Wizard's den, and the Syndicate Teleporter. Once you have left it, this z-level is only accessible by the Mining Shuttle and by teleportation.
Mining
This level is immediately recognizable by the many asteroids, and contains the Mining Outpost. Miners who do not join late will start here. The Mining Shuttle can be used to travel from the Mining Outpost to Engineering on the Station Z-Level. This level can be accessed through random space exploration.
AI
This level contains the AI Satellite, the AI Satellite teleporter, and the remains of Zeta station. It can be accessed through random space exploration, and in addition, there is a teleporter beacon. The AI Satellite teleporter has tools and equipment to build a working teleporter but is missing one pane of glass, so it is possible to strand yourself there.
Donut / H7
This level contains the remains of Donut Station, Hemera 7, and the Soviet Derelict. It is accessible through random space exploration.
Centcom
This level contains Centcom and The Maze. The former is only accessible by the Emergency Escape Shuttle; the Maze is only accessible through specially hacked VR pods and admin fiat.
Syndicate Shuttle
This level contains the Nuclear Operative's shuttle. It is only accessible with a Syndicate Teleporter Remote.