Photography is both an "art" and a "science." The "art" concerns itself with images that are aesthetically pleasing to the eye, a photograph's composition. Understanding the "art" is essential to good photography, but cannot be performed by itself. The "art" employs and applies principles from the "science" to accomplish what the photographer desires. One cannot learn and master it first and then take photographs. It requires practice, experimentation and study to determine how use of principles from the "science" affect the appearance of the photograph. Intertwined in this are some references to elements of the "art" as the "science" is studied and used as tools for the "art." This is not intended to be in depth on any particular aspect of the "science" but an overview of its most important elements.