Active systems are technologies or processes that require energy input to function and respond to changes in their environment. These systems actively monitor conditions and make adjustments to maintain desired outcomes. Examples include smart thermostats that regulate temperature based on user preferences and automated irrigation systems that optimize water usage based on soil moisture levels. In contrast to passive systems, which rely on natural processes, active systems often incorporate sensors, controllers, and actuators. This allows them to perform tasks like controlling lighting in buildings or managing traffic flow on roads, enhancing efficiency and user experience.