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.

The Books were an American duo, formed in New York City in 1999, consisting of guitarist and vocalist Nick Zammuto and cellist Paul de Jong. Their releases typically incorporate samples of obscure sounds and speech. They have released three critically acclaimed albums on the German label Tomlab, and released their fourth studio album, The Way Out, on Temporary Residence Limited in July 2010.

Zammuto and de Jong first met in New York City in 1999 as they shared the same apartment building. De Jong invited Zammuto to dinner at his apartment, where he played him some of his collection of audio and video samples, including a Shooby Taylor record. Zammuto said of their meeting that "we both kind of knew at that moment that we listened (to music) in interesting ways and had similar approaches to music." Soon after, they began playing what they considered to be pop music, in comparison to their own works, under the name The Books.

In 2000, The Books started work on what would become their début album Thought for Food. Zammuto and de Jong moved locations constantly during this time, recording in New York, Los Angeles, Boston, and finally in the basement of a hostel in North Carolina where Zammuto worked for a while after hiking the Appalachian Trail.

Chip Kidd (born September 12, 1964) is an American author, editor, and graphic designer, best known for his book covers.

Born in Reading, Pennsylvania, Kidd grew up in the Reading suburb of Shillington, strongly influenced by American popular culture.

Kidd is currently associate art director at Knopf, an imprint of Random House. He first joined the Knopf design team in 1986, when he was hired as a junior assistant. Turning out jacket designs at an average of 75 a year, Kidd has freelanced for Doubleday, Farrar Straus & Giroux, Grove Press, HarperCollins, Penguin/Putnam, Scribner and Columbia University Press in addition to his work for Knopf. Kidd also supervises graphic novels at Pantheon, and in 2003 he collaborated with Art Spiegelman on a biography of cartoonist Jack Cole, Jack Cole and Plastic Man: Forms Stretched to Their Limits. His output includes cover concepts for books by Mark Beyer, Bret Easton Ellis, Haruki Murakami, Dean Koontz, Cormac McCarthy, Frank Miller, Michael Ondaatje, Alex Ross, Charles Schulz, Osamu Tezuka, David Sedaris, Donna Tartt, John Updike and others. His design for Michael Crichton's Jurassic Park novel was carried over into marketing for the film adaptation. Oliver Sacks and other authors have contract clauses stating that Kidd design their books.

Albert Einstein ( /ˈælbərt ˈaɪnstaɪn/; German: [ˈalbɐt ˈaɪnʃtaɪn] ( listen); 14 March 1879 – 18 April 1955) was a German theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics. While best known for his mass–energy equivalence formula E = mc² (which has been dubbed "the world's most famous equation"), he received the 1921 Nobel Prize in Physics "for his services to theoretical physics, and especially for his discovery of the law of the photoelectric effect". The latter was pivotal in establishing quantum theory within physics.

Near the beginning of his career, Einstein thought that Newtonian mechanics was no longer enough to reconcile the laws of classical mechanics with the laws of the electromagnetic field. This led to the development of his special theory of relativity. He realized, however, that the principle of relativity could also be extended to gravitational fields, and with his subsequent theory of gravitation in 1916, he published a paper on the general theory of relativity. He continued to deal with problems of statistical mechanics and quantum theory, which led to his explanations of particle theory and the motion of molecules. He also investigated the thermal properties of light which laid the foundation of the photon theory of light. In 1917, Einstein applied the general theory of relativity to model the structure of the universe as a whole.