Photography, defining it in one word or a paragraph is not enough. Not even books written on it can define it completely. To start with, I would say its an art form. Painting with light to be accurate. It’s the only way to freeze a memory in passing time. May be we like it so much because at least for once we are in control of time. It gives us power. Power of a higher order (Time travelling in a subtle form).
An art form has become common in today’s modern world, most of us all know how to take one picture and had take a photo. (Though it is beautiful or not, still photography).