vincy

The official definition of the title attribute is - "The title attribute specifies extra information about an element.". In other words it's used to provide additional information about an element (in your case an image) that hasn't already been mentioned either as an alt attribute or figure caption.
 
For example using a FIGURE tag:
<figure> <img src="mypicture.jpg" alt="" title="A decorative radiator from the 1920's"> <figcaption>Photo of a cast iron radiator</figcaption> </figure> ...or using a standard IMG tag
<img src="mypicture.jpg" alt="Photo of cast iron radiator" title="A decorative radiator from the 1920's"> You don't have to use a title attribute every time, it really depends on whether the extra information is useful.
 
Does that help?