If it seems like everyone in your neighborhood has double hung windows, that’s because they are the most popular window type in the U.S.  This type of window is composed of an upper and lower sash that can be moved up and down independently of each other, with each sash capable of being tilted inward for easy cleaning and maintenance. If you are replacing your home’s windows, particularly second-story windows where cleaning the window exteriors from the inside is preferable, double hung replacement windows are a great choice.