Modulators are substances or devices that influence the activity of other molecules or systems. In biology, they can enhance or inhibit the effects of neurotransmitters, which are chemicals that transmit signals in the nervous system. For example, certain drugs act as modulators by adjusting the response of receptors to neurotransmitters, thereby affecting mood, pain perception, or other physiological processes. In technology, modulators are used in communication systems to modify signals for transmission. They can change the amplitude, frequency, or phase of a carrier wave, allowing information to be sent over distances. This is essential in devices like radios and televisions, where modulators help convert audio and video signals into a format suitable for broadcasting.