Layering

Layering is a game design tool that prevents player overcrowding in outdoor areas of World of Warcraft: Classic. It is effectively the same as sharding, but covers the entire outdoor world of a realm.

Behavior
At the launch of Classic, players on overcrowded realms were grouped into different "layers". Each layer is a copy of the outdoor world, with minor differences:


 * Players can only see other players on the same layer.
 * Each layer has its own set of NPCs. As such, rare NPCs may respawn at different times on different layers.
 * Each layer has its own set of objects such as herbs and mining nodes.

Players can move to a different layer by joining a party with a party leader on a different layer.

Blizzard originally intended to merge the layers of each realm before Phase 2. This was made effective in November 13, 2019.