The word Photograph is derived from the greek words phos & graphê meaning light drawing. The best way to control light is providing your own.
Why not just use the SUN ?? apart from a short duration in the morning & evenings (on a clear day) the sun is just too bright and results in harsh shadows around objects and areas of a face. The only way to have 100% control over light is to head indoors into a studio where you can plan every ray of light to work the way you want.
A Studio (derived from the latin word studere, meaning to study) is a workroom. A Studio is place where you can minimise the effect of sunlight and also have enough space to move around with your subject & equipment.