PDF files or portable document format files are a cross-platform files which means they can be opened and read both on Mac and Mac operating systems. This file format was created by Adobe Systems in 1993. PDF files are created by Adobe Acrobat or a program with the Acrobat plug-in. PDF is generally used for saving files for viewing on multiple computers. PDF files may have text, images, forms, outlines and other data. PDF is a format is able to keep intact the formats, fonts, drawings and other file components of any document file and exhibit it in a universal format across all platforms independent of application software, hardware and operating systems. PDF files are generally created from another document format instead of creating them originally from beginning and can be edited with Adobe Acrobat. PDF files can be viewed using the Adobe Reader or the Adobe Reader plug-in, which is available for almost all the Web browsers. Some browsers, like Google Chrome, provide intrinsic support for viewing PDF files even without the Adobe Reader plug-in. Also, PDF files in Firefox can be viewed with the PDF.js extension.