Your professor may request one or another of these common textbooks.  The truth is that they are really all more or less the same.  I prefer Stokstad’s Art History for an introductory historical survey,
as I have found it to be more accurate than the others, and also containing fewer outdated, Western-biased or sexist passages.  Still, they are all very similar, and you could probably use any of them for any such course.

Every year or two, the publishers put out new editions, and they are more or less identical

Key Texts in Art History

Guides to Writing about Art

I consider these two perfectly interchangeable.  Both are quite helpful in suggesting approaches to writing about art, providing strong examples, and covering the major points of visual analysis.  Either one can really be a help for those first few art history essays you will have to write.

Art History Surveys

Marilyn Stokstad, Art History

This handy “portable edition” lets you buy just the volumes that you need, and each is small and light, in case you want to bring it with you to class.

Janson’s History of Art

One of the standards in the field (and the first art history text I used).  This is the two-volume version, though it is also available in one, or in six.

Gardner’s Art Through the Ages

The third of the major surveys, also available in multiple formats.