# Virtual Sensor
Virtual Sensors are virtual assets explained in [asset types](/asset/asset-types.md#virtual-assets).
It creates an option to you create a source without a physical device representation. There is three type of virtual sensor: Virtual Value, Virtual Form, Virtual Simulation.
Virtual Value is often used when you need a empty sensor that you can set output of a rule without interacting with physical device data.
Virtual Form is often used when you want a simple placeholder sensors that store constant data. You can enter your constants or variable within a simple form.
Simulation is a virtual representation of a physical device or a situation with some custom configurations.
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