Short answer: Don't use them, except in special circumstances.
HTML title
attributes are often perceived as an accessibility (and SEO) bonus, but the opposite is true. For screen reader users the content included inside of the title
attribute is typically unncessary, redundant, and possibly not even used. Conversely, content being put in the title
attribute is being hidden from the (probable) majority of your users. If information is being hidden from the majority of your users, then it's probably not necessary.
There are a few times when using a title
attribute is appropriate:
- For
<frame>
and<iframe>
elements - For providing a label when a text label would be redundant
Rule of Thumb: Serve all users equal content.
- Steve Faulkner has an in-depth post on "Using the HTML title attribute" (Jan 15th, 2013)
- RNIB Blog: TITLE attributes (May 16th, 2007)
rather than redundant or unnecessary, according to this article, the title attribute is generally not read by default (except in forms and i/frame) unless they change the setting. Admittedly the article a little old, but from what I've been told by those with some experience of screen readers, it still holds true.
http://www.rnib.org.uk/professionals/webaccessibility/wacblog/Lists/Posts/Post.aspx?id=38