Measured in degrees, the beam angle describes how wide the light is spread. Bulbs with a narrow beam angle create a spotting effect and are suitable for highlighting particular features of a room. Bulbs with a wide beam angle create a flooding effect and are better for general ambience.
The most common beam angles for the domestic home are 24-26 degree (medium) or 36-38 degree (wide). Beam angles can be as low as 6-8 degrees to produce a precise spot of light to the 100 degree plus beams for very general floodlighting.