Search Engine Forums, SEO Forum

Hi
Image alt attribute is certainly significant for SEO and usability. It serves the users mentioned above with enriched website usability and also returns images in relevant search results due to enhanced site SEO

No, If you had not used image alt tag for images, your website will not penelyze by Google. But it is a good practice to use image alt tag.

Not necessary, if you want to promote the keywords mean then concentrate on that image as well