alt tag is good for best website optimization. it is help to optimize your image. it will help to improve your ranking.
Yes, they may help increase your keywords rankings in serp if you put some keywords on alt tags. Though its effects is just a minimal. So better not to overstuff your keywords in alt tags. Other role of alt tags is for user-navigation. For example, if some of your site's images are not loading properly, alt tags will be displayed.
In my opinion alt tags will improve keywords density. They will also appear in image searches. So basically I think they help for SEO.
Thery're also used by screen readers - their main purpose is for accessibility. But adding in a few keywords won't hurt
I would recommend the use of the alt tag. It definetly won't have a negative impact so its worthwhile doing.
Alt tags are important as the search engines identify the images . Also optimise the images for Google Image search
yes ALT Tag Play some factor for SEO point of view. because search engine don't know that with is your image/logo/picture is you can tell them via ALT Tag to Search Engine. it's basically use of image optimizations.