Robotics simulators represent the world in software. They range in complexity from the simple and only operate in a top-down 2D world, or very complex with photo-realistic rendering and physics modeling.
(Image from v-rep)
This is a pretty comprehensive list of robotics simulators lifted from this old (and closed) StackExchange question.
A list of some robot simulators:
- Player Project (Stage is a 2D simulator, Gazebo is a 3D simulator with physics engine, opensource)
- MORSE (general purpose indoor/outdoor 3D simulator)
- Microsoft Robotics Studio (simulator + control interface)
- KiKS (Matlab plugin, only for Khepera + control interface)
- MobotSim (for point-like robots, more of algorithm implementation )
- Karel (Pascal/Logo like)
- Webots (closed source)
- Simbad (2D/3D simulator in Java and Jython)
- Robocode (A Java/ .NET suit)
- Rossum's Playhouse (C/C++ suit)
- V-REP (3D, source available, Lua scripting, APIs for C/C++, Python, Java, Matlab, URBI, 2 physics engines, full kinematic solver, etc.)
- OpenRAVE (C and Python interfaces, 3D, optional physics engine integration)
- Robotics Toolbox (Matlab toolbox)
Some references on robot simulators:
- Development environments for autonomous mobile robots: A survey
- Open source robotics toolkits
- Updated review of robotics software platforms
- Existing Simulators - firstname.lastname@example.org
- List at Asaf Matan's website
Typically, a simulator will either be for mobile navigation, or manipulation. Although more and more these are converging.