Start by opening any LibreOffice app. Since Writer is the tool I use the most, I'll open Writer. With LibreOffice Writer open ...
One of my former clients only accepted Word documents, back when Office was still called Office, so I used LibreOffice Writer ...
Examples are Microsoft Office (Word, Excel and PowerPoint), Apple's iWork (Pages, Numbers and KeyNote) and Linux-based LibreOffice (Writer, Calc and Impress). All office suites are able to read ...