Will the spiders for adsense read only the visible html text? Or do they also read image alt tags, titles and meta tags? Is there a certain amount of keyword frequency plus density that your page needs for google to display relavent ads?
My pages - well a few of them will have text content but a lot of it is visual and/or graphic text instead of html. I can easily put the text that's in the graphics into an alt tag for the grapic so the spiders can read it but I don't know if the go by this or only read this visable html?And if so, is there a certain amount of html I need on the page?