How Google Wants You To Use Alt Tags & Title Tags on Images

• alt attribute should be used to describe the image. So if you have an image of a big blue pineapple chair you should use the alt tag that best describes it, which is alt="big blue pineapple chair."
• title attribute should be used when the image is a hyperlink to a specific page. The title attribute should contain information about what will happen when you click on the image. For example, if the image will get larger, it should read something like, title="View a larger version of the big blue pineapple chair image."