There are the following options you could use to backup or add version control to your Salesforce configuration or Apex code:
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- Only editing code or making configuration can change in a Sandbox or Developer Edition. This actually keeps your changes sever from your production instance in case something goes wrong, and if the Sandbox gets too messed up, you can always refresh it from production and start clean.
- Subversion can be used through the Force.com Eclipse IDE for version control.
- You can also create multiple Sandboxes.