Attribute for <AREA ...>
ALT = "text string"

Usage Recommendation
use it

ALT, which works just like <IMG ALT="...">, indicates the alternative text to use for the link if the browser does not display the image (for example if the user is blind and uses a text browser). If you decide to put an imge map in your web page, don't look like an amateur and leave out alternate text.

For example, the following <AREA ...> tag indicates that the alternate text is Contacts:

<AREA 
   HREF="contacts.html" ALT="Contacts" 
   SHAPE=RECT COORDS="6,116,97,184">

which gives us the rectangle in this map:

Some visual browsers do not utilize the ALT attribute but make user the TITLE attribute to display a prompt over the area, so it's a good idea to use both:

<AREA 
   HREF="contacts.html" ALT="Contacts" TITLE="Contacts" 
   SHAPE=RECT COORDS="6,116,97,184">

which gives us this map: