Requirements of RichTextEditor
RichTextEditor control will automatically determine the browser that has requested the page and render the appropriate solution for that browser. However, some control features cannot be rendered on older browsers.
Browsers are split into two distinctive groups: "uplevel" (newer versions) and "downlevel" (earlier versions). Uplevel browsers are defined as IE 11, all Internet Explorer versions from 6.0 up on Windows, Firefox 2.0+, Chrome, Mozilla 1.3+, Netscape 7+, Opera 9.x and Safari (1.3+). This includes Macintosh and Linux. RichTextEditor will render rich UI in uplevel browsers.
Downlevel Browsers are split into different groups as well. By further determining browser capabilities, RichTextEditor may render as simple UI, BBCode Editor, Mobile UI(iPad, iPhone, Android) or a regular textarea.
Keep in mind that you don't need a supported browser to see HTML pages generated
using Rich Text Editor, you just need a supported browser to edit with Rich Text
Web Server Requirements: