ISR

ISR is an acronym used in multiple fields. In military and security contexts, it stands for Intelligence, Surveillance, and Reconnaissance. It denotes coordinated activities to collect, analyze, and disseminate information about potential threats, targets, and environments. Components may include imagery intelligence, signals intelligence, human intelligence, and open-source data, delivered through aircraft, satellites, ships, drones, and ground sensors. The aim is situational awareness, informed decision-making, and improved mission planning, often supported by a structured collection management process and PED (processing, exploitation, and dissemination) of data.

In computing, ISR means Interrupt Service Routine. An ISR is a software routine that executes in response to a hardware interrupt, such as I/O completion or a timer event. ISRs are designed to be fast and lightweight, preserve processor state, and minimize work to avoid latency. They typically acknowledge the interrupt, perform a small amount of work, and defer longer processing to a lower-priority task or thread. Proper ISR design is essential for real-time and embedded systems.

ISR also stands for Induced Systemic Resistance in plant biology, a broadly acting immune response triggered by beneficial microbes or certain stimuli. It primes plants to better resist subsequent pathogens and pests, often involving hormonal signaling and gene regulation. As with other acronyms, the meaning of ISR depends on context.