Can optimizing the Alt text for images benefit normal search results ranking,or is the ranking signal from it just for image search?
JOHN MEULLER (Webmaster Analyst from Google):
I believe we part of a text on a page. So in that regard, we would also pick that up there. But for the most part, we pick up enough information about the page from the rest of the content on the page. So usually there’s not a need to stuff extra information into the Alt text. I really try to use the Alt text for what it was really made for– for helping describe the image that is there rather than to stuff additional keywords in there that you might not have visible on the page itself.