Welcome to ITKE, nevaca! Here’s a great definition from WhatIs.com that should point you in the right direction.
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The Whatis.com definition has become slightly out-of-date in that the “current” version of Microsoft Word does support ODF documents. However, for somewhat older versions, an ODF Add-in for Word, Excel or PowerPoint, might be helpful. It might even be reasonable recipient to download and install an open source suite such as LibreOffice to have an alternative suite available. — Tom