So, What Makes A Photograph A Photograph?

A photograph is typically defined as a "Frozen Moment Of Time". But, it isn't necessarily the scientific element of the photo that makes it what it is, but the content. Whats actually inside the frame could be seen as what the photograph is, as it can create a different meaning for everyone.
It could be a photo of family, a friend, that one moment where the moon looked "REALLY PRETTY", or Aunt (insert aunt's name here) dancing on top of the table at your cousin's wedding.
But, the photograph wouldn't even be able to have a meaning at all if it wasn't for the scientific side.
Light is primarily composed of 7 different colours from the electro-magnetic spectrum. The range of these colous that we call "Visible Light" ranges from 400 to 700 nanometres. Anything beyond that range means that we can't see it. Light from objects in the frame of view *rebound * into the lens of the camera, and are then processed by the camera's processor, or exposed onto film, if you're using a 35mm camera, or another of the film kind.
Or, you could be artistic about it, and take into account the content of the photo, compisition, colour, etc...

That, in my opinion, is what makes a photograph.