Your PC draws a sizeable amount of power, and it’s susceptible to damage from power surges—small, temporary increases in voltage coming through the power line. These can happen after power outages, after turning on another high-power device in your home, or could just come from an unreliable power grid in your city. The power supply inside your PC includes some basic surge protection, but you’ll get longer-lasting protection from a dedicated surge protector.
Note that this is different from a power strip, which provides multiple outlets without the protection from surges. Be sure to replace it every three to five years, too, since that protection wears out over time—if yours is old, there’s a good chance it’s offering zero protection.
Keep in mind that surge protector won’t protect against high-voltage spikes (like lightning), but it can protect you from smaller surges and extend the life of your PC. If you have a few more dollars to spend, you might even want to get an uninterruptible power supply (UPS), which contains a battery backup that prevents your PC from shutting down and losing data during a sudden power outage.
Lastly, laptops require a bit more care due to their portability. While a desktop’s power cable can sit stationary for years at a time, your laptop cable goes with you everywhere, subject to kinking, hard yanks out of the wall, and other mishandling. This can not only make the cable unreliable, it can pose a fire hazard, so always pull the charger out of the wall from the plug, not the cable—and don’t wrap it too tightly.