The way that you save a document and the format that you save it in depends on how you plan to use the document. For example, if the document is for your own use and you never expect to open it in a previous version of Microsoft Office Word, the simplest way to save it is to use the Save command, using all the default settings.
However, if you are posting the document for others to open, if people reading your document are using software other than Microsoft Office Word 2007, or if you intend to open the document on another computer, you need to choose how and where you want to save the document.
If you commonly save documents in a particular place or format, you can adjust settings so that Word defaults to these choices.