Web documents and the .pdf format.
Some personal computers, and in particular the Ubuntu (Linux) types
have the ability to read this specific document format as their native document handler.
The Portable Document Format (PDF) was created by Adobe Systems in 1993 for document exchange.
It was officially released as an open standard on July 1, 2008, and was published by the International Organization for Standardization as ISO/IEC 32000-1:2008.
The aim is to use a file type so that a multitude of documents - instructions, guides and so on,
are easily read even if your PC "has" the "wrong version" of the "word processor software".
If your computer cannot "open" these .pdf format files it is possible to download a free reader from Adobe Systems.
Their site should detect what version you require and help you to install the reader software.