A container that helps you organise and track shading nodes (materials, textures, etc.) in your scenes. It is accessible from the Hypershade window.

A default master bin contains all shading nodes in your scene, but to quickly locate shading assets you can add other bins and give them strategic names (for example, wood, metal, doors, foliage). When a node is assigned to a bin, all its input nodes are also assigned to this bin.