Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Well-organized, clear, and to the point

This is *the* book a new technical writer should read. Barker really knows his stuff--and he presents it in truly usable form. I especially liked his 3-category approach: writing to teach (for eager learners), to guide (for reluctant users of the product), or to provide a reference (for experts who need only occasional support).