Real-time refers to a mode of operation in which a system responds immediately to changes in its environment or inputs, with little or no delay. In computing, real-time systems are those that can process and respond to input signals within a predetermined time interval, typically measured in milliseconds or microseconds. Real-time systems are used in a variety of applications, including process control, telecommunications, and multimedia processing. For example, a real-time video conferencing system would need to transmit and display audio and video data in real-time, without any noticeable delay or lag, to ensure a smooth and natural conversation. Real-time performance is critical in many modern computing applications, as users expect fast, responsive systems that can keep up with their needs.