The description of pdf format expansion
The pdf file object is a cross-platform document opened and generated by Adobe Acrobat or another application based on PDF algorithm. The PDF extension is often applied for saving publications and documents compressed via a general algorithm. Afterwards such a document can be easily viewed on multiple platforms. In much of the cases, PDF files are based on existing documents rather than being created from scratch.
PDF files may include outlines, annotations, forms, images, text and other data. They maintain formatting and fonts electronically across multitude of various platforms and appear identically on the screen as well as while being printed on paper. A lot of web-browsers, such as Google Chrome, guarantee native support for PDF viewing without the external Adobe Reader module. Firefox is able to view PDF files with the PDF.js extension.