Since their invention in the 1920s, electric garage door openers have come a long way. Garage door openers work by using a trolley connected to an arm that attaches to the top of the garage door and slides back and forth on a track, which opens and closes the garage door. When operating the motor, a chain or belt turns and pulls the trolley along the track. A good garage door opener will have a horsepower of 1/2 HP, 3/4 HP, or 1-1/4 HP. Garage door openers have the ability to open and close a limited number of times in power outage emergencies. Security is something else to consider when purchasing an opener. It's helpful to have sensors that will stop the operation of the garage door when a person, vehicle, or other obstacle is in the way.
I'm not a professional, but I watched as my garage doors were serviced last year. The tech used a spray lubricant (I had bought a different brand in the garage door section of a home improvement store). He sprayed the inside of the entire track, top and bottom, the rollers that ride along the track, and all hinges on the door. He sprayed each hinge twice -- once on each side. The techs were more generous with the lubricant than I was when I'd done it before, so don't be afraid to give it a good squirt.