Book

A book is a set of pages bound together along one edge, usually with a cover, that holds writing or pictures for someone to read. Books can tell stories, explain how things work, teach a skill, or share poems and ideas. They are one of the oldest tools humans have invented for saving knowledge and passing it on.

People made books long before there was paper. The ancient Egyptians wrote on scrolls of papyrus, a plant that grows along the Nile River. The ancient Chinese wrote on strips of bamboo tied together with cord. The Maya folded long strips of bark into pages that opened like an accordion. The kind of book most familiar today, with flat pages bound at one edge, is called a codex. Romans began using codices around 2,000 years ago.

For most of history, every book had to be copied by hand. A single copy of a long book could take a monk a whole year to finish. That made books rare and expensive. A farmer in medieval Europe might never see one in person.

Everything changed around 1450, when a German named Johannes Gutenberg built a printing press that used movable metal letters. Suddenly, hundreds of copies of the same book could be made in the time it once took to copy one. Books became cheaper. More people learned to read. Ideas spread faster across Europe than ever before. Many historians call the printing press one of the most important inventions in human history.

Books come in many shapes today. There are picture books for young children and thick novels with hundreds of chapters. There are textbooks, cookbooks, comic books, and graphic novels. Some books are now digital, read on a screen as e-books or listened to as audiobooks.

Many people thought e-books would replace paper books. So far, they have not. Paper book sales have stayed strong, especially for kids' books. Researchers are still studying why. Some think it is because paper makes it easier to remember what you read. Others think people just like the feel of a real book in their hands.

The biggest library in the world is the Library of Congress in Washington, D.C. It holds more than 170 million items, including over 40 million books. If you tried to read every book on its shelves, you would never finish in a lifetime.