Plain English Meaning
An online tool pilots can use to see whether a chunk of military or restricted airspace is hot, cold, or scheduled to be hot at a particular time, so they know whether they can fly through it.
Full Definition
A web-based FAA system that publishes the real-time scheduling and activation status of Special Use Airspace (SUA), such as Restricted Areas, Military Operations Areas, and Warning Areas. It allows pilots to check whether a specific piece of SUA is currently active, scheduled to be active, or released back to the controlling agency before and during a flight.
Context Anchor
You may see SAMS mentioned when studying how civilian pilots can plan around, or sometimes fly through, special use airspace.