This is an additional accessory which is connected to the opener motor. When the mains power goes out, the motor gets powered by the battery and you can operate the door automatically. If you opt for such an accessory, you should check how long the battery can last for in standby mode and how many cycles the door can make with it. The higher the numbers are the better.
If you’re using your garage as a workspace other than for parking your car, you may wish to look for a garage door with a higher R-value. You should also check the quality of your weather seals and see if they're in need of replacing or repair. Garages can be one of the main sources of energy escape for attached houses so its wise not to overlook it.
Don't ever underestimate any garage door problem. They are all important enough to need immediate garage door repair. A missing bolt is almost equally serious with having misaligned garage door tracks. Every part has its own reason for being there so make sure issues are solved fast.
A backup battery is an excellent idea for every home with an automatic garage door system. It will come in very usefully during a power outage and they can last for up to twenty-four hours from the moment the power goes out.