They are intended for, and written at a level appropriate to, an educated lay readership.
Each volume takes complex scientific concepts and provides explanations that can be easily understood.
For example, Albert Einstein's theory of relativity is explained in a cartoon about a spy drama involving a train traveling very close to the speed of light; probability is explained with poker hands; and the periodic table of the elements is conveyed with common household items.
Although progress has overtaken much of the material in the more than 50 years since their publication, the series' explanations of basic science and the history of discovery remain valid.
This article about a book on biology or natural history is a stub.