By default, Word documents are saved in the .docx file type. However, there may be times when you need to use another file type, such as a PDF or Word 97-2003 document. It’s easy to export your document from Word to a variety of file types.
Exporting your document as an Adobe Acrobat document, commonly known as a PDF file, can be especially useful if you’re sharing a document with someone who does not have Word. A PDF file will make it possible for recipients to view—but not edit—the content of your document.

If you need to edit a PDF file, Word allows you to convert a PDF file into an editable document.