Underlining and italicizing mean the same thing in writing. It is correct to underline book titles when handwriting or using a typewriter because those methods of writing cannot utilize the italics that are used in printing and typesetting. However, when writing on a computer, it is generally considered correct to italicize titles of books and movies. Technically it's a thing of preference. What
. is important, however, is consistency and compliance with whatever style manual is being used. Some grammatical elements which are generally italicized:
Titles of books (though short stories use quotation marks) Names of periodicals and magazines (though not government documents) Movies and plays (whereas songs use quotation marks) Television series (however specific episodes use quotation marks) Works of art Names of vessels Foreign words not in common English usage Scientific nomenclatureThere are many different style manuals people use when writing reports (e.g. MLA, Chicago, APA, etc) most of which can be accessed online. Many school reports use MLA format, but a picky teacher should specify. For more information, please see: http://www.reference.com/browse/style+manual 