answer:.docx is not a compression format… that’s the default format for the latest version of Word 2007 (as part of Office 2007). Your friends are likely running older versions of Word, and hence cannot open that file. Same would be true for .xlsx (Excel), etc. Use the Save As… dialog and choose a type of “Word 97–2003 document (*.doc)” and then everything should look right to you and your friends. To permanently set your default save-as type to be plain old ”.doc” like you’re used to, bring up that Save As… dialog again. In the lower left corner, there’s a “Tools” button, click that. Choose “Save Options…” from the pop-up and in the resulting dialog, select your preference for “Save files in this format”.