By its very nature, Drupal is a Content Management System (CMS). Unlike web sites that are built around image libraries or shopping carts, a CMS is driven by content, usually in the form of text, images, videos, and the like. Creating, editing, and "filing" content is as fundamental an operation in Drupal as is doing the same with your financial transactions in Quickbooks.
Simply having a large amount of text in a giant repository would make the task of finding and using what you need excruciating. A good CMS makes it easy for you to add, organize, and use content. Think of a magazine. Some pages are entirely composed of one story. Some have two or more articles of related content, and some, two or more articles of unrelated content. In order to compose a page comprised of small articles about leafy green vegetables, you have to be able to create and find them. Drupal provides the creation and arrangement of pieces, and this is what you will learn next.