Google Docs keeps track of all the changes you make to a document. If you accidentally or intentionally make some changes and want to revert to an older version, simply drag it from the revision history list.
The first program to incorporate WYSIWYG technology was Bravo. This document preparation program was developed for the Alto computer designed at the Palo Alto Research Center of Xerox. Though Bravo was never released commercially, its direct descendant was included in the Xerox Star. WYSIWYG, Ethernet, GUI, bitmap graphics and several computer technologies that we used today have been developed at the Xerox's Palo Alto Research Center (PARC). [more...]