LaTeX is a software system for document preparation that is used for the communication and publication of scientific documents in many fields, including mathematics, computer science, engineering, physics, chemistry, economics, linguistics, quantitative psychology, philosophy, and political science. LaTeX is not a word processor, but a document preparation system that uses plain text as opposed to the formatted text found in WYSIWYG word processors like Microsoft Word, LibreOffice Writer, and Apple Pages. LaTeX is based on the idea that it is better to leave document design to document designers, and to let authors concentrate on getting the right content. LaTeX uses the TeX typesetting program for formatting its output, and is itself written in the TeX macro language. LaTeX can be used as a standalone document preparation system, or as an intermediate format. In the latter role, for example, it is sometimes used as part of a pipeline for translating DocBook and other XML-based formats to PDF. LaTeX is especially well-suited for scientific and technical documents, and its superior typesetting of mathematical formulas is legendary. LaTeX is available for nearly every operating system, like Windows, Linux, Mac OS X, and many more, and its file format is plain text—readable and editable, on all operating systems. LaTeX generates PDF output—printable and readable, on most computers and looks identical regardless of the operating system. Besides PDF, it supports DVI, PostScript, and HTML output, preparing the ground for distribution both in print and online, on screen, electronic book readers, or smartphones.