Files with the RTX extension are used for storing text documents. This format was developed by Microsoft. However, RTX files are supported by many editors not only developed by Microsoft. In addition to text, RTX documents contain information about its format (font, text formatting elements, page layout, etc.). Illustrations from files such as JPG or PNG are often added to such documents.

As RTX is recognized by many editors, it is often used as an exchange format between different applications and system platforms. RTF extension is used interchangeably for these files.