This document summarizes different types of sliding doors. It discusses the history of sliding doors dating back to Roman houses in the 1st century AD. The two main types of sliding door gears are top hung systems and bottom rolling systems. Top hung systems have hangers at the top of the door running in a concealed track, while bottom rolling systems have two rollers at the bottom running on a track. The document also describes different types of sliding doors including bypass doors, surface doors, pocket doors, and bifold doors. Pocket doors slide into pockets in the wall, while bifold doors have hinged panels that fold against each other. In conclusion, sliding doors are easy to use but can be more costly than standard panel doors