Image optimization 101: How to rank higher in image search

SEO is not only about optimizing written content. The increasing dominance of visual content online has brought with it new opportunities for increasing a site’s search traffic by optimizing videos and images. Optimizing your images  gives your website an additional chance to be found via image search, and a good logo or some eye-catching graphics can be just as effective at attracting visitors to your website as your written content

See the rest here:
Image optimization 101: How to rank higher in image search