A multi-cache is a cache type that takes you to more than one location before reaching the final destination.
Some multi-caches have a container, tag, magnet, or other object at each stage. Each stage but the final one holds information (e.g., coordinates) that you need to find the final container.
Other multi-caches (e.g., offset caches) use "virtual" stages without containers (like virtual caches). The location of the final stage is determined from information found on existing objects (e.g., monuments, plaques, public art).
Also, multi-caches with more than two stages can be either "serial" or "parallel". With serial caches, only the location of the first stage is published, and each stage provides the location of the next. With parallel caches, the locations of all stages but the final are published, and each of these stages provides part of the information needed to find the final.