Terminology

• World: The term used to describe a collection of robots and objects (such as buildings, tables, and lights), and global parameters including the sky, ambient light, and physics properties.

• Static: Entities marked as static (those having the <static>true</static> element in SDF), are objects which only have collision geometry. All objects which are not meant to move should be marked as static, which is a performance enhancement.

• Dynamic: Entities marked as dynamic (either missing the <static> element or setting false in SDF), are objects which have both inertia and a collision geometry.

Reference: http://classic.gazebosim.org/tutorials?tut=build_world