Faq/General/021/en

What is the file format used by LibreOffice?
LibreOffice saves its data in OpenDocument format (ISO 26300:2006 standard). OpenDocument is based on XML. This requires the presence of several files and subdirectories in the document. This is completely transparent to the user as LibreOffice collects everything in a ZIP file (a compressed file format) and LibreOffice affects its own extensions to the created files.

To verify this: You will then see the XML file structure with among others: For more information on XML, you can refer to the FAQ entry LibreOffice and XML.
 * Create a text file with LibreOffice e.g.
 * Rename the file to.
 * Open the file with an unzipping program (e.g. 7-zip).
 * : the only text of the document;
 * : the description of paragraph styles, page, etc.. ;
 * contains the images;
 * Etc.