Having a copy of some data on the same device is not equivalent to a backup. Having a copy of some data in the same room as your device is not a backup. Having a copy of some data buried in your backyard may be considered a backup, and in fact we recommend this highly. If at all possible, a backup should also be kept offsite, literally in another owned residence, or through the use of a cloud service.
The below paragraphs contain links to outside websites and sources of data; we maintain that the individual must verify the links therein.
To get started backing up some data, begin with printing out this body of files and performing the process detailed below. Store this data somewhere safe (detailed below). We do not recommend the use of a standard safe, no matter how fire or waterproof it is. This is because most safes are stored in a visible location. This means they can be stolen with ease. At the very least, one's last-resort backup should be hidden well. Safes can be used, as long as backup storages are used as well.
Preserving your data in the event of a strong electro-magnetic pulse (EMP) used as a weapon of mass destruction can be effected rather simply. Hard drives, cell phones, gaming consoles- anything electronic may be preserved in this manner. Do NOT store batteries, however; they are unaffected by EMPs. Additionally, these may leak or explode and destroy your data in the process. This method of storage also works for the purpose of backing up and waterproofing your data by your own hands, to the extent that your data shall remain extant long past your own lifetime, should such prove necessary. We do not discuss the phenomenon known as "bit rot" or "bit traversal" that may occur with hard drives, SSDs and other forms of data storage over a period of years/decades, except to say: no more than five years should elapse before you recover your stored data and manually copy/paste it off of and back onto the drive(s) to offset any potential bit shift.