Window air conditioners are probably what most of use think of when we hear the word "air conditioner".
Over the years, this type of air conditioner has become much more sophisticated. They now come with many more features than they did years ago. Some even connect to applications on your smart phone so you can cool your space down before you reach home. Try doing that with a unit from the 1970's. Most importantly, they are much quieter than they used to be. So, if you are a light sleeper, your air conditioner no longer needs to keep you up at night..