In biology, feedback inhibition refers to the mechanisms that control certain processes and functions within cells, the body and even the environment. At its most basic, feedback inhibition means that when some sensor gets a certain amount of feedback from the environment, it turns another system on or off.
One example of this in biology is how cells control the proteins and other substances that come into them. If the cell sends the feedback to the control mechanism that the substance levels inside the cell are too high, the control mechanism will stop letting the substance into the cell. Conversely, if the substance levels are too low inside the cell, the control mechanism will receive feedback to let more inside.