A smart developer keeps habit of taking daily backup of the produced artifacts, otherwise machine crash can crash you as well. You should keep your artifacts at your local machine as well as another secure machine, so that in case of machine crash, you can continue with the saved copy of the source code or documents.
If you have the habit of taking daily backup then in worst scenario you may lose at most one-day effort, but if you take weekly or monthly backup, then there is a risk of losing whole-week or whole-month effort, and you will face biggest disappointment you ever had.
This is true that having backup is one of the most important best practices, but it should be maintained in well managed way as you can use tags like name, date and time of the backup, version, etc. If you have multiple copies of the same source code or document, then it will create confusion and it would be difficult to identify latest code or document.
It is strongly recommended to use proper source code version control system. There are many source code version control software applications available for free (like SCCS, CVS, Subversion etc.) which you can use to store different versions of the software. But while using a source code control system, follow the rules below:
Love, affection, friendship and relationship are on top of everything, but never embrace anybody asking for password.
If you are sticking to first point, then why you would share your password with anyone if you are not asking from anybody.
Keep changing it on a frequent basis and it's good if you have some logic to drive your passwords, otherwise during your long vacation, you will forget them.