Systems behavior: what do we call an information system that responds immediately to events in (or needs of) the physical system it supports?

Introduction / Context:
Many applications must react to events as they occur: process control, stock trading, airline seat inventory, and medical monitors. These are distinct from batch systems that process accumulated data later. The distinguishing term emphasizes immediate responsiveness.

Given Data / Assumptions:

• The system interacts closely with a physical or operational process.
• Response must be immediate or within strict time constraints.
• The question seeks the standard term for such systems.

Concept / Approach:
A realtime system guarantees timely responses. It may be hard real-time (missed deadlines cause failure) or soft real-time (degraded quality if late). “Online” simply means connected/interactive but not necessarily time-bounded; “offline” processes later; “inline” is not a standard category.

Step-by-Step Solution:

Verification / Alternative check:
Control systems, avionics, and high-frequency trading literature use the term “real-time” to indicate deterministic or bounded-latency responses.

Why Other Options Are Wrong:

• Online/on line: Interactive but not necessarily time-critical.
• Offline: Batch; not immediate.
• Inline: Not a standard systems category.

Common Pitfalls:
Equating “online” with “real-time”; ignoring latency guarantees required by true real-time applications.

Final Answer:
realtime system