What does Beam Angle mean in the Lighting Industry?

Also known as the beam spread. It is angle of the light pattern emitted from the center part of the beam of a lamp where the luminous intensity is 50% of the maximum.

Beam Angle Common Name Good For
15° Spot Very high ceilings (15ft or higher) or where a finely focused light is required on a subject.
20-25° Narrow Flood Higher ceilings (10ft or higher) or where a larger focused light than a spot is required on a subject.
40° Flood Normal ceilings (8 - 9ft) or where a traditional light spread is required.
110° BR Flood Even distribution of light in focused areas.