In "wiki" words:
A photogram is a photographic image made without a camera by placing objects directly onto the surface of a photo-sensitive photographic paper and then exposing it to light.
In my own words:
I whack all kinds of objects on top of some photo-sensitive photographic papers, develop them in my little darkroom, check them out, scan them in and upload them here...
I upload ALL my photograms/rayographs to my photogram-blog, so some are good and some are not, but it is a chronological archive of my exploration of developing original photograms/rayographs.