Document file formats can contain real documents, of one or more pages. There are many different formats due to different uses (text, spreadsheets, presentations, etc..)
Most popular softwares for document are LibreOffice and Microsoft Office, that most people recognize by the name of the softwares in contains such as Microsoft Word, Microsoft Excel, Microsoft Powerpoint.
Compatibility problems
As of today, sharing documents can still be complicate because documents can appear differently when opened on two different PC.
Document formats
Text
Spreadsheet
Presentation
Document softwares
Microsoft Word
LibreOffice Writer
Microsoft Excel
LibreOffice Calc
Microsoft Powerpoint
LibreOffice Impress