overheating on 1996 Volkswagen Jetta

What purpose does the sensors in the the thermostat housing performs and what is the names of the , yellow, blue and brown sensors.

Asked by for the 1996 Volkswagen Jetta
these are your temperature sensors for the fan, ecu and gauge, they are all neede for the computer to run the engine properly, also the termosthat not only regulates temperature but also regulates coolant flow trough out the block, head,heater core, do not take it out as it will only make the overheating worst.
Thanks very much for your answer, it has given me some insight on how the system works.