It's all about the idea!!!! The concept is the most salient aspect of the photo....whether it makes you laugh or think or cry. If you are not familiar with conceptual photography check out the work of Misha Gordin at www.bsimple.com/ and you will get the idea.
Again, it is all about the idea, often based in language, like puns, or idiosyncratic expressions.
Also, it is depicting non-concrete concepts iconographically..... www.erwinolaf.com/Pages/Adv_Frms.htm
