A regulator is a person, organization, or device that controls something to keep it working properly or following the rules.

In government and business, regulators are officials or agencies that make sure companies follow laws designed to protect people. The Food and Drug Administration (FDA) is a regulator that checks whether medicines are safe before doctors can prescribe them. Banking regulators make sure banks don't take dangerous risks with people's money. Environmental regulators set limits on pollution from factories. These regulators create rules, inspect businesses, and can punish companies that break the law.

In science and engineering, a regulator is a device that maintains steady conditions. A voltage regulator keeps electricity flowing at a constant level so your phone charges safely. A pressure regulator on a scuba tank controls how much air flows to the diver. Your body has natural regulators too: your pancreas acts as a blood sugar regulator, releasing insulin to keep your glucose levels steady.

Whether it's an agency enforcing safety standards or a thermostat controlling temperature, a regulator's job is keeping things within proper boundaries. Without regulators, systems can spin out of control or become unsafe.