Levels & World Partition

A UWorld is the running game world. It always has one persistent level (UWorld::PersistentLevel) and any number of streamed levels. For large worlds, World Partition — the default for new projects in UE5 — replaces hand-managed sublevels with automatic spatial streaming around streaming sources.

When to use this skill

• Organizing world content across levels and keeping memory under control.
• Building an open world or large level that cannot be fully resident.
• Toggling sets of actors at runtime (day/night, story states, destruction phases).
• Making reusable, instanced level chunks (buildings, modular areas).
• Working with legacy explicit sublevels in a project that predates World Partition.

Core mental model