Thread:SEOkitten/@comment-26955746-20150902011746/@comment-26321732-20150902205537

You are right! The file name should be as descriptive as possible since search engines cannot tell images apart; spiderman_slinging_webs.jpg is better for SEO than img012.jpg.

Descriptions in the summary/description section of the file page provide more keyword content for the search bots and appear in search results as the meta description (that short description of a page that appears beneath a listing in search). Meta descriptions are the advertising copy for a link, so improving them can bring more clicks and visitors to a page.

Search algorithms consider hundreds of on-page and off-page factors; it is almost impossible to influence or determine the reasons for a single search result. There are some tests that we would like to run related to this, and I will be sure to share the results on the Community Central blog if we discover anything conclusive.

This topic is top of mind for our team, so it's good to hear others are thinking about it too!