As you can probably tell, this choice searches the materials the library owns by titles (and titles in tables of contents, if available). Unlike Keyword searches, however, this searches only titles and looks at the exact title. This means all those little of's, for's and from's make a difference in finding the title you want in the catalog.
Use this choice if you are sure of the name of the book(s) you want to find. If you aren't so sure try a Keyword search instead.