Resource books are perhaps the purest form of non-fiction book because they are used to record basic facts so that they can be dipped into for clarifying information.
Both the dictionary and the thesaurus are resource books. The dictionary defines the meaning of all words, and the thesaurus offers synonyms for a given word.
The encyclopedia is perhaps the most extensive of resource books since it is a compendium of information covering all branches of knowledge.
This is the most popular form of non-fiction book. Either form is written about the individual life experiences of a single person, but while an autobiography is written by the individual whose life is being recounted, a biography is written by a third party.
Biographies, and particularly autobiographies, can be among the most inaccurate of "factual" books due to memory being unreliable or records having been lost.
History books record the details of time periods and events. Accurate history books are written with reference to documentation.
However, while history textbooks arguably present mostly basic facts, many history books written by academic historians present more historical theory.
Science studies and text books are intended to relay scientific findings. Because these findings are based on the results of controlled tests and experiments, often these books have a more limited possibility of containing overt opinion.
A familiar example of a scientific non-fiction book is "On the Origin of the Species" by Charles Darwin.
The most common form of guidebook is a travel guide. Travel guides contain useful bits of practical information about hotels, restaurants, attractions and other necessary information on a given location.