You should make a habit of saving your work often. This helps to ensure that your files are saved in the event of a power interruption or a hardware or software problem.
The first time you save a new document file, you can name it and choose where you want to store it. Afterwards, each time you choose the Save command, any changes to the file are saved.
The Revert to Saved command lets you quickly reload a previously saved version of a document. Use this command to undo all changes you have made to a document since the last save.