Candela (cd) measures luminous intensity—light power per unit solid angle in a specific direction. While lumens measure total output in all directions, candela measures directional brightness. This matters for spotlights, track lights, and reflectors where beam concentration is critical. 1 cd ≈ light from 1 candle. Relationship: lumens = candela × steradians. A typical LED spotlight with 15° beam angle and 2,000 cd center beam delivers focused accent lighting for retail displays.