Green: the system is coping
Apps may use most installed memory while pressure remains green. That is typically healthy: the system is using RAM for active work and reclaimable cache.
Yellow: watch the trend
Yellow indicates that compression, cache eviction, or swap is doing more work. A brief yellow period during a demanding task may be fine; sustained yellow with lag deserves investigation.
Red: reduce demand
Red pressure means the system is struggling to satisfy demand efficiently. Save work, close an unneeded high-impact app normally, and verify that pressure falls. Restarting can provide temporary relief but does not identify a recurring cause.
Compression and swap are context
Compressed memory lets macOS fit more active data into RAM. Swap moves inactive pages to disk. Neither is automatically bad, but rapid growth paired with elevated pressure and slow response is meaningful.
A better diagnosis
MemoryPilot charts pressure over time beside top app groups, free/reclaimable memory, and compression so you can decide whether to wait, close an app, or investigate further.