Описание тега richtext
Text that includes formatting commands for page layout such as fonts, bold, underline, italic, etc. It may also refer to a multimedia document that can include images, audio and video.
The Rich Text Format (often abbreviated RTF) is a proprietary document file format with published specification developed by Microsoft Corporation since 1987 for Microsoft products and for cross-platform document interchange.
Most word processors are able to read and write some versions of RTF.