Even earlier than MSN Messenger was the RTF document format, promoted by Microsoft as an interoperability format to allow them to co-exist with Microsoft Word in a market dominated by WordPerfect, WordStar, etc.

And of course Microsoft dropped RTF like a hot potato when they managed to use their new Microsoft Windows platform to leverage into a huge market advantage for Microsoft Word. Other vendors were obviously initially reluctant to spend enormous resources to port their software to Windows, a competitor’s platform, but Microsoft could spend hugely on developent of Microsoft Word for Windows, making it very impressive graphically, and when the Windows platform was successful, all other word processing software vendors were left behind, forced to play catch-up. I also remember hearing that Microsoft were using secret Windows APIs to get nice things like toolbar icons in color, not available to non-Microsoft companies.