Pictograph of rising flames. As a radical 火 marks characters about fire, heat, cooking, and combustion — 灯 (lamp), 烟 (smoke), 炒 (stir-fry), 烤 (roast), 烫 (scalding), 燃 (ignite). The bottom variant 灬 (four dots of fire) appears under 热, 煮, 蒸, 焦, where it preserves the same heat semantics.