A photograph or photo is an image created by light falling on a light-sensitive surface, usually photographic film or an electronic medium such as a CCD or a CMOS chip. Most photographs are created using a camera, which uses a lens to focus the scene's visible
wavelengths of light into a reproduction of what the human eye would see. The process and practice of creating
photographs is called photography. The word "photograph" was coined in
1839 by Sir John Herschel and is based on the Greek φῶς (phos), meaning "light", and γραφή (graphê), meaning "drawing, writing", together meaning
"drawing with light".
Photography is the science, art and practice of creating durable images by recording light or other electromagnetic
radiation, either chemically by means of a light-sensitive
material such as photographic film, or electronically by means of an image sensor.
Source: Wikipedia