A book is a set of written, printed, illustrated, or blank sheets, made of ink, paper, parchment, or other materials, usually fastened together to hinge at one side. A single sheet within a book is called a leaf, and each side of a leaf is called a page. A book produced in electronic format is known as an electronic book (e-book).

Books may also refer to works of literature, or a main division of such a work. In library and information science, a book is called a monograph, to distinguish it from serial periodicals such as magazines, journals or newspapers. The body of all written works including books is literature. In novels and sometimes other types of books (for example, biographies), a book may be divided into several large sections, also called books (Book 1, Book 2, Book 3, and so on). A lover of books is usually referred to as a bibliophile or, more informally, a bookworm.

A store where books are bought and sold is a bookstore or bookshop. Books can also be borrowed from libraries. In 2010, Google estimated that since the invention of printing, approximately 130,000,000 unique titles had been published.

Philosophy is the study of general and fundamental problems, such as those connected with reality, existence, knowledge, values, reason, mind, and language. Philosophy is distinguished from other ways of addressing such problems by its critical, generally systematic approach and its reliance on rational argument. The word "philosophy" comes from the Greek φιλοσοφία (philosophia), which literally means "love of wisdom".

The introduction of the terms "philosopher" and "philosophy" has been ascribed to the Greek thinker Pythagoras. The ascription is said to be based on a passage in a lost work of Herakleides Pontikos, a disciple of Aristotle. It is considered to be part of the widespread body of legends of Pythagoras of this time. "Philosopher" was understood as a word which contrasted with "sophist" (from sophoi). Traveling sophists or "wise men" were important in Classical Greece, often earning money as teachers, whereas philosophers are "lovers of wisdom" and not professionals.

The main areas of study in philosophy today include epistemology, logic, metaphysics, ethics, and aesthetics.

Bertrand Arthur William Russell, 3rd Earl Russell, OM, FRS (18 May 1872 – 2 February 1970) was a British philosopher, logician, mathematician, historian, and social critic. At various points in his life he considered himself a liberal, a socialist, and a pacifist, but he also admitted that he had never been any of these in any profound sense. He was born in Monmouthshire, into one of the most prominent aristocratic families in Britain.

Russell led the British "revolt against idealism" in the early 20th century. He is considered one of the founders of analytic philosophy along with his predecessor Gottlob Frege and his friend Ludwig Wittgenstein, and is widely held to be one of the 20th century's premier logicians. He co-authored, with A. N. Whitehead, Principia Mathematica, an attempt to ground mathematics on logic. His philosophical essay "On Denoting" has been considered a "paradigm of philosophy." His work has had a considerable influence on logic, mathematics, set theory, linguistics, computer science (see type theory and type system), and philosophy, especially philosophy of language, epistemology, and metaphysics.

Ayn Rand ( /ˈaɪn ˈrænd/; born Alisa Zinov'yevna Rosenbaum, February 2 [O.S. January 20] 1905 – March 6, 1982) was a Russian-American novelist, philosopher, playwright, and screenwriter. She is known for her two best-selling novels The Fountainhead and Atlas Shrugged and for developing a philosophical system she called Objectivism.

Born and educated in Russia, Rand moved to the United States in 1926. She worked as a screenwriter in Hollywood and had a play produced on Broadway in 1935–1936. After two initially unsuccessful early novels, she achieved fame with her 1943 novel The Fountainhead. In 1957, she published her best-known work, the philosophical novel Atlas Shrugged. Afterward she turned to nonfiction to promote her philosophy, publishing her own magazines and releasing several collections of essays until her death in 1982.

Rand advocated reason as the only means of acquiring knowledge and rejected all forms of faith and religion. She supported rational and ethical egoism, and rejected ethical altruism. In politics, she condemned the initiation of force as immoral and opposed all forms of collectivism and statism, instead supporting laissez-faire capitalism, which she believed was the only social system that protected individual rights. She promoted romantic realism in art. She was sharply critical of the philosophers and philosophical traditions known to her besides Aristotle.