the short answer
Steady-state cardio is continuous aerobic exercise held at a comfortable, even intensity - think brisk walking, easy jogging, cycling, or rowing for 30-60 minutes at a pace where you could still hold a conversation. Its strengths are an aerobic base, better recovery capacity, and a low fatigue cost that makes it easy to sustain. It is not a fat-loss shortcut: the calories burned add to a deficit, but diet sets the deficit.
This article is general coaching information, not medical advice - individual needs vary, and any client with a heart condition, very low fitness, injury, or other medical concern should be cleared by a doctor before starting or increasing cardio.