Required Reading: Classic resources you shouldn't research without.

Limners and tappers and bothes, oh my! Next time an unfamiliar term stymies your research, consult A to Zax: A Comprehensive Dictionary for Genealogists and Historians by Barbara Jean Evans (Heritage Books). It explains thousands of little-used and old-fashioned words and abbreviations - medical, legal, religious, occupational, monetary, geographical, ethnic and colloquial vocabulary - that will help you decipher old documents. The book's a true bargain considering how often you'll reach for it, and it's compact enough to take along on research trips. (In case you were wondering: A limner is a self-taught traveling artist, a tapper is an innkeeper and a bothe is a storehouse or a shop where goods are sold.)