If your body is dehydrated, the control center in the brain will stimulate the release of a hormone which causes the reabsorptio
n of water into the blood during urine formation. When the control center senses that enough water is reabsorbed, it will stop the release of the hormone. This is an example of a negative feedback mechanism
Negative feedback mechanism is the process by which the output of a system, process or mechanism is fed back into the input in order to reduce the error in the system.
In the system described in this question, the reabsorption of water is the output, a feedback signal is sent to the control center, which is the input in order to control the release of the hormone responsible for reabsorption of water into the blood.
