Rembrandt is generally considered one of the greatest painters. Rembrandt lighting is characterized by an illuminated triangle under the eye of the subject on the less illuminated side of the face.
If you want to learn more about how to achieve this look then read my earlier blog post where I show some the student's work from a workshop I did in Kona, Hawaii with the School of Photography at Youth With A Mission here.
Create Triangle with Off Camera Flash
Another triangle used by professional photographers is the triangle created between the camera, subject and flash.
Create Triangle with Subject
One other way the triangle is used in photography is in subject placement within a frame. Putting subjects in a group photo in triangles creates a pleasing composition.
Create Triangle with Gear
To make your camera stable we also use a triangle. Three legs to our tripods and light stands create very stable platform for our camera and light stands.
May the triangle be ever present in your photographs: from lighting, composition and support.