Almost everything a business depends on now exists as data: the customer list, the invoices and accounts, the orders in progress, the files and photos and records that would be painful or impossible to recreate. Most owners know, in the abstract, that they should back this up, and many do have some kind of copy somewhere. The trouble is that a single backup often turns out to be no backup at all when it is actually needed - it was on the same computer that failed, or the external drive that was stolen along with the laptop, or a copy that quietly stopped updating months ago and nobody noticed.
The failures that destroy business data tend to hit everything within reach at once, and that is the key insight behind a good backup plan. A drive can fail, but so can the building it sits in be affected by fire, flood or theft, and a growing category of attack deliberately encrypts every file it can reach - including any backup connected to the same machine or network at the time. A backup that is always plugged in and always online is exposed to the very same event as the original. So the goal is not just to have a copy; it is to have a copy that the disaster cannot reach.
This is what the widely used 3-2-1 approach captures in a form small businesses can actually follow: keep at least three copies of important data, store them on at least two different types of media or location, and keep at least one copy offsite and offline - disconnected from the day-to-day system. In practice that might mean the working files on the main computer, an automatic copy to a reputable cloud service, and a periodic copy onto an external drive that is then unplugged and stored somewhere else. The exact tools matter less than the shape: more than one copy, in more than one place, with one that is out of reach of a live problem.
Two things turn a backup plan from theory into protection. The first is making it automatic where possible, because a backup that depends on someone remembering to do it manually will eventually be forgotten precisely when things are busy. The second, and the one most often skipped, is testing that a backup can actually be restored - occasionally recovering a file from it to confirm the copy is real, current and usable, rather than discovering only in a crisis that it was empty or corrupt. Backups are cheap insurance against one of the few events that can end a business in an afternoon, and the small effort of setting them up properly, and checking them now and then, is out of all proportion to what they protect.