What is art?

Is this art? Who will be the judge of our Photoshop Neodadaist work? Will it ever be held up and judged, or does the impermanence of the digital world stand to separate? Did not the first man or woman to scratch a man with a spear and a penis into a cave wall do this in an attempt to leave their mark, to leave something of themselves in this physical world? If leaving your mark is the essence of art, where does that leave digital art? Is it art?