alt tags should only be used to describe images. Look at the code of my website [snip] I'm a freelance web designer. Please drop me a link with your page so I can have a look. If you used only images on your home page (this is quite common for photography websites) then alt tags would describe images used. However if for some reason standard text is closed in ALT then this practice should be changed.
hope this helps
[edited by: brotherhood_of_LAN at 8:37 pm (utc) on Apr 4, 2014] [edit reason] no personal urls, see the terms of service. thanks [/edit]
I've actually found, fairly subjectively speaking, that alt tags are the least important for ranking an image out of
- on-page content - image URL - alt tag
I've often seen images rank based on just the URL for a specific search if the rest of the site supports the general area. For example, if you had a site all about flowers and the on-page content was all based on common names, but the URL includes the Latin name, you might get some traffic for searches on the Latin name. But of course, you'll get your butt kicked for all the usual reasons by a site that actually has good on-page content.
In general, uncaptioned slideshows are hard going to be really hard to rank for. 90% of the time when I end up on slideshow page, it's because I got suckered by one of those ads at the bottom of the page on Huffington Post or some other news outlet where the ads look like links to actual editorial content.