I wired in a box outside our basement for a generator when the ice storms were supposed to come through two years ago. It is similar to a dryer hook up, just turn the generator on outside, turn off the main breaker to your house so you aren't backfeeding the line, plug in the generator to your outlet, turn that breaker on in the panel and then you have some electricity to run some essential things like a fridge, some lights, and maybe the stove/ oven depending on how big of a generator you have.
Try restarting a bakery when the power goes out... We have 2 bread lines and a bun line each with 3000 amp main breakers. When the power goes out you have about 6-7 people running around in the dark trying to get the whole plant started up in about 15-20 minutes, if you have all three phases. If you don't check to make sure you have all three phases before you charge the breaker up and flip the contacts close and single phase all those motors you probably wouldn't have a job tomorrow lol.