What's mean by "alt" ?

Answer 1

alt means alternative,if an image doesn't show in web then message written in between alt tags,shows

Answer 2

It's a description of the image in case it doesn't load correctly in the page or the url is lost

Answer 3

don't forget guys. you can cheat a bit with the alt tag for search engines. use the alt text to describe your business by using a keyword phrase. No more than 3 words. Ok you learned something. also the tag is used for people that surf without images turned on.