The Chicago Manual of Style (abbreviated in writing as CMOS, TCM, or CMS, or sometimes as Chicago) is a style guide for American English published since 1906 by the University of Chicago Press. Its 17 editions have prescribed writing and citation styles widely used in publishing. It is "one of the most widely used and respected style guides in the United States". The guide specifically focuses on American English and deals with aspects of editorial practice, including grammar and usage, as well as document preparation and formatting. It is available in print as a hardcover book, and by subscription as a searchable website as The Chicago Manual of Style Online. The online version provides some free resources, primarily aimed at teachers, students, and libraries. Availability and uses The Chicago Manual of Style is published in hardcover and online. The online edition includes the searchable text of both the 16th and 17th—its most recent—editions with features such as tools for editors, a citation guide summary, and searchable access to a Q&A, where University of Chicago Press editors answer readers' style questions. The Chicago Manual of Style also discusses the parts of a book and the editing process. An annual subscription is required for access to the online content of the Manual. (Access to the Q&A, however, is free, as are various editing tools.) Many publishers throughout the world adopt "Chicago" as their style. It is used in some social science publications, most North American historical journals, and remains the basis for the Style Guide of the American Anthropological Association, the Style Sheet for the Organization of American Historians, and corporate style guides, including the Apple Style Guide. The Chicago Manual of Style includes chapters relevant to publishers of books and journals. It is used widely by academic and some trade publishers, as well as editors and authors who are required by those publishers to follow it. Kate L. Turabian's A Manual for Writers of Research Papers, Theses, and Dissertations also reflects Chicago style. Chicago style offers writers a choice of several different formats. It allows the mixing of formats, provided that the result is clear and consistent. For instance, the 15th edition of The Chicago Manual of Style permits the use of both in-text citation systems and/or footnotes or endnotes, including use of "content notes"; it gives information about in-text citation by page number (such as MLA style) or by year