I know that the alt= attribute is recommended for SEO propososes, but I also heard that put the description inside a div and hide with text-indent:-9999px or font-size:0; is a good practice for SEO. So there is any difference between use:<img alt=Descripition />or<div style=background: url('path/to/img')>Description</div>
Which one should I use for SEO proposes? text or 
seo;html;css;images;alt attribute
For images that you want to get crawled use the <img> tag with a well-written altattribute that describes the image.For background images solely used for design use the CSS background-image. As far I know CSS rules will not add value to your sites SEO but if CSS is used to hide contents from users and is only visible to search engines that might hurt your sites SEO.