We choose to purchase many books after reading what reviewers have to say. Vendors, however, bring the books to us for personal examination. Holding the book in our hands gives us a very good idea of whether or not a particular book will actually be used once it's in the collection. We can examine the table of contents and personally observe the reading level and how well it matches that of the students most likely to use the information. We can observe charts, graphs, and pictures and determine whether or not a particular volume complements our collection or overlaps what we already have. And once we've established a relationship with a vendor, they know which books are most likely to pique our interest.