What is a photograph?

I recently spent a coupe of weeks in Japan and visited a photography museum in Tokyo. There was an exhibit showing the winners of an international journalist competition. There was also an exhibit showing the progression in the techniques for printing photographs. As I walked around the two exhibits I began to think about what a photograph really is, and this came to mind:

“A photograph captures moments that are an expression of daily life or emotion. Through form, colour and light it captures style , form , architecture, an expression of something made (nudes, buildings, shadows). It can be a reflection of oneself.”