The Material Explorer lets you browse and manage all the materials in a scene.
While the Material Editor lets you set the properties of individual materials, it is limited in the number of materials it can display at any one time. With the Material Explorer, you can browse all the materials in a scene, see the objects to which a material is applied, change material assignment, and manage materials in other ways.
Interface
The Material Explorer interface has two panels: the upper Scene panel and the lower Material panel. The Scene panel is similar to the Scene Explorer, in that it lets you browse and manage all the materials in the scene, while the Material panel lets you browse and manage the components of a single material.