A table of contents, usually headed simply "Contents" and abbreviated informally as TOC, is a list of the parts of a book or document organized in the order in which the parts appear. The contents usually includes the titles or descriptions of the first-level headers, such as chapter titles in longer works, and often includes second-level or section titles (A-heads) within the chapters as well, and occasionally even third-level titles (subsections or B-heads). The depth of detail in tables of contents depends on the length of the work, with longer works having less. Formal reports (ten or more pages and being too long to put into a memo or letter) also have table Within an English-language book, the table of contents usually appears after the title page, copyright notices, and, in technical journals, the abstract; and before any lists of tables or figures, the foreword, and the preface.