The term "backup" is high ambiguous. A number of genealogy programs, including the venerable Personal Ancestral File (PAF), have a file option called "backup" included in the menu. Although the term is used, choosing this option does not in fact make a backup copy of your data. In the case of PAF, the program makes a compressed copy of your file on the same disk as the original, unless you specifically direct the program otherwise. In my experience, those who use this command simply because they have been told to do so, rarely, if ever make a separate copy of their file on another device.
What is a backup copy of your file? As clearly as I can explain the concept, it is a separate copy of your data file on a completely separate disk or other media. When you create a new file in any program including genealogy programs, the program saves the new file to your hard drive. Unless you tell the program otherwise, the file is likely saved in some default location on your hard drive. Sometimes the programs save the file to a default "My Documents" file on Windows Operating Systems. Sometimes the file is saved into a file folder created and named by the program and located in the folder containing the copy of the program file. This is usually the case with Macintosh systems unless you have designated an alternative place for the file to be saved.
Many of the current genealogy programs have menu selections that allow you to designate where you would like your "backup" files to be recorded. However, unless you make this selection, the program will save files in whatever default location is set by the developer of the program.
This problem of where files are saved is not unique to genealogy programs. Normally, without intervention, all user created files, depending on the programs' defaults, will be saved in different folders on your hard drive. Word processing documents in one location. Genealogy files in another location. Photographs and other graphic files in yet another location. Before you can properly backup any part of your computer system, you need to get control of the location where your files are stored. It is very common for me to find genealogists who have several, sometimes many, copies of their data files all over their computer's file system. Often, they have no idea which of these duplicate files is the most recent and may have added data to different files at different times. Sometimes they are even surprised to find out they have duplicate files at all.
My method of solving this problem is to create one file folder, which I keep on my desktop level, where I save any and all my data file, from any and all my programs. This puts almost all of the data files in one place. There are a few exceptions with programs that will not allow their data files to be located outside of the same folder containing the program. If I cannot work around this problem, I make sure I am not using that particular program for the creation of any of my own primary data files, i.e. files I want to keep.
Backing up all of my data files then just involves making a copy of the singe data file (usually called "James" or whatever) onto an external hard drive. Now, in the case of my iMac computer, I use Time Machine which makes a complete copy of my hard drive many times a day. I use a 2 Terabyte back up external hard drive that can continue to keep the updated copies for many weeks and months back. In addition, I make another separate copy of the data file and anything else of value, on a different external hard drive. From time to time, I also make a backup copy onto a portable external hard drive and give the copy to one of my children somewhere around the country.
This last step is important. To have a true backup of you data, not only does the copy have to be separate from your main computer, it also needs to be offsite. If your house burns down or is broken into, you could still lose an onsite copy. Any time I do a significant amount of work, like hundreds of additional scans or a lot of writing, I also make copies onto separate computers in addition to the external hard drive backup. One of those is a laptop which I usually carry with me on trips. Just in case.
You could make a copy onto a flash drive. In my case, my files exceed the size of the largest currently available flash drive. But in your case, you may be able to use a flash drive. But I suggest also making a copy on an external hard drive and don't forget to store a recent copy with a friend or relative. (Good friend and good relative).
Some people suggest storing your data online. I am not really happy with that idea. In my case that type of storage would be relatively expensive in both money and time. I am not convinced that any one of the online storage companies will be there functioning in three or five years, so I am reticent about using online storage. It is a viable option, if you also have a local and offsite copy of all of your data.
Some people use safety deposit boxes. I don't. As a probate attorney, I have handled many, many probate cases and had a significant number of problems gaining access to safety deposit boxes. Also, because of the difficulty of gaining access to the safety deposit boxes, you are not as likely to make incremental backups. I suggest that because of data migration issues and accessibility, safety deposit boxes would not be my first (or second, or third) choice.
Whenever you make a copy of your files. Make sure the copy is able to be used and open. I am also skeptical of compressed files. With cheap storage readily available, there are no longer practical reasons for backing up files in a compressed format. There are still programs, such as PAF, that use a compressed file format for their "backup" files. I do not like this idea because over time the program that makes the compressed file, like Windows Zip, will change and may not work to unzip the files.
All computer storage is dynamic, that is, subject to change. I will address the issue of file migration in a subsequent post.