the short answer
NEAT - non-exercise activity thermogenesis - is the energy you burn through all daily movement that is not deliberate exercise: walking, standing, posture, fidgeting, and everyday tasks. It is the most variable part of daily energy expenditure, often swinging by hundreds of calories, which makes it the biggest lever most clients have for fat loss outside the kitchen.
This article is general information for coaches, not medical or clinical nutrition advice. Coaches help clients build movement and nutrition habits - if a client has a suspected metabolic or medical issue, refer them to a doctor or registered dietitian.