Theory Books are books which consist of rules, assumtions, estimation and views on a definite subject. These books are generally based on rules and processes in a subject or chapter.
Theories do not rely on what people feel but rather on what is true.
It is true that theories are based on true facts which are verified before putting them in theory books. Theories are derived from facts and it can be well explained with an example. Fruits fall, from trees on the ground. This is a fact and the theory behind this fact is gravitational pull of the earth. So facts and theories go hand in hand. There is theory for every fact.
Theory books are an important part of the syllabus in schools, colleges and universities.
