A subject not talked about much in the SEO world is Link Title Attributes and whether they have any benefit in SEO. To understand this topic and to see if it was worth me putting any effort into doing, I did some research and came up with my own conclusions. I welcome all other SEO specialists to share their thoughts on this topic and help me and others get a better understanding of this.
First of all, I want to describe the attribute to help those of you like me understand its “intended” purpose. According to W3.org, the title attribute "offers advisory information about the element for which it is set." W3 goes on to state that "visual browsers frequently display the title as a "tool tip" (a short message that appears when the pointing device pauses over an object)." and “setting the [title] attribute on a link allows user agents (visual and non-visual) to tell users about the nature of the linked resource.”
The title attribute can be used to describe almost any HTML element. A beneficial way to use the title attribute for SEO purposes would be to use it in the link element to provide descriptive text within an anchor tag (which gives you more real estate for your targeted keyword phrases). I would suggest not to duplicate your anchor text (for usability purposes). It's supposed to provide supplementary information and let the users know where the link will direct them to if they click on it. When creating your link titles, optimize for keyword phrases you’re targeting on the linked to page (just as you would with anchor text). Search engines only use them in consideration to the page being linked to, not the page the link is on.
Source: Moz
