What is Atl tag?

[Jeffreyhooft]

An alt tag is the information which appears when the mouse hovers over an image. This tag is a very good place to add keywords which are relevant to that page and that image. They should be kept short and snappy and should contain enough information to convey the picture’s purpose but should not be overly long and complicated.

[braketech]

optimizing every image for its particular importance is necessary. Search engines always loves to see alt & title tags in a webpage for crawling. These helps in improving the presence of your keywords ranking.