They are made with a series of horizontal slats (hence the name) that hang one on top of the other from a ribbon or cord. They are attached to the top of your window frame via a mechanism comprising of a cord through which up and down movement of the blind is done.
They are made of metal, vinyle, pvc or plastic or wood. Slats can be opened or closed to bring in and block outside light by the use of cord provided. These types of blinds are mainly used for smaller, narrower and taller windows.