If you have any video game cartridges in your possession that save progress to the cartridge, then you'll have to face the sad fact that sooner or later (probably sooner), your beloved save data will shuffle off to the big memory card in the sky as the little batteries that power the memory that retains your progress die. While changing out that decaying battery with a fresh one is something that has become more common in recent years, what do you do about the save data being kept on life support by a dying battery? Sure, you can change the battery, but your progress will be lost in the process. Is it possible to keep it alive and well during cartridge surgery? Platypus Comix explains how with some effort, your prized Pokémon or masterful EarthBound accomplishments can survive a battery swap.
The good news is, someone came up with a solution to preserve Game Boy saves. The bad news is, that was a LONG time ago, back when that kind of cartridge was still being used. If you hunt around, you may be able to find the Game Boy Transferer 2, but you may have a harder time finding a port on your PC for the gigantic plug the device takes.
Over half the people searching for a way to rescue Game Boy saves have Pokemon in mind -- that may be what brought YOU to this page. Those old cartridges hold dozens of irreplaceable creatures from your childhood, and the batteries keeping them in existence aren't getting any younger.
I have yet to find a dead battery in my collection, although admittedly it's been years since I powered up some of the cartridges in my personal library. I may have a cemetery of progress on my shelf and not even know it. Still, while it would sting to lose my adventures in EarthBound or The Legend of Zelda: Ocarina of Time, the fun of video games is replaying them all over again, so I suppose that... no, who am I kidding? I worked hard for that Sword Of Kings and, damn it, I want to keep it around as long as possible.