Windows might seem like pretty basic things to us in modern life but the true reason for their invention dates back to the days when the world was haunted by creatures from other planets. The first homes that human beings constructed had no windows at all. The reason for this was that the creatures that used to roam the lands loved to hunt humans to eat them and houses needed to have no openings that showed light or allowed for smells to come out of the homes. If one of these creatures saw any kind of activity in the home construction, they would know that humans lived there.
The creatures did not have enough logical thinking to know that most homes would have humans inside, but once they detected movement they would attack relentlessly until they caught their victims. Once the order eradicated them from the planet the celebration included the symbol of freedom that is now known as a window.