Vim 7.0 and later support undo branches. This feature prevents the loss of changes, even if you switch back to an earlier state of your text and start editing there. A change in this context is considered as all editing you have made while in insert mode, or a single editing command in normal or command-line mode. As soon as you leave insert mode a new change will start. It is important to leave insert mode so you will really create a new distinct change to which you can later move back, otherwise all changes that are done while you are in insert mode will be considered the same change. While in insert mode, you can also press Ctrl-G then u to break the undo sequence and start a new change. In fact, it is probably a good idea to automatically do this in some situations, for example so you