response

Response is the act of replying or reacting to a stimulus, prompt, or input. It can be a verbal reply, a physical action, a physiological change, or a data payload generated by a system. The term appears across disciplines with overlapping meanings, and the specifics depend on context. In everyday language, a response is what someone says or does in reply to a question, event, or message.

In biology and medicine, responses include reflexes, immune responses, and hormonal changes. Reflexes are rapid, involuntary actions mediated by the nervous system to protect the body from harm. Immune responses involve recognizing pathogens and mobilizing cells and molecules to neutralize them. The magnitude and timing of a biological response depend on factors such as stimulus strength and prior exposure.

In computing and information technology, a response is the data returned by a server after a request. An HTTP response, for example, consists of a status code, headers, and a body. Response time—the delay between request and reply—affects user experience. Systems may generate asynchronous, streaming, or chunked responses, and caching or load balancing can modify observed response behavior.

In statistics and research, the response variable (dependent variable) is the outcome measured to assess the effect of predictors. Modeling aims to quantify how changes in inputs influence the response.

In communication, responses include verbal replies, backchannels, and other turn-taking signals that convey attention, agreement, or confusion. Effective responses are timely, relevant, and appropriate to the context.