The document discusses real-time data and its applications. Real-time data refers to data that is processed and delivered immediately without delay. It provides up-to-the-minute information from devices and sensors. Some key applications discussed include stock exchanges, advertising, weather monitoring, transportation and traffic management, live video processing, and smart cities using Internet of Things technologies. The distinction between real-time, near real-time and non-real-time data is also explained based on the processing time and delay involved. Real-time systems require both logical and time-based correctness and are important where precision and response time are critical factors.