Window shades refer to any window covering meant to hide the interior of the home from the view of passersby (thus, the use of the word 'blind'). Depending on the material and mechanism involved, they can also be an effective means of controlling the amount of sunlight that enters a room.
Common types
The two most commonly used kinds of shades are slat blinds and solid blinds.
Slat blinds are made of horizontal, flat slats, or panels. By rotating a string device that connects all the slats, you may tilt the slats upwards to let in some light or downwards to keep out light. The entire shade can also be pulled up to clear the entire window. Slat blinds are usually made of metal or vinyl.
Unlike slat blinds, solid blinds have no mechanism to allow light to pass through it. They hang over the window to keep out light completely and can be pulled or rolled up to clear the window. There are several kinds of solid blinds, including roller shades (also known as Holland blinds), pull-down shades, pleated fabric shades, and Roman shades.
Other functions of window shades
Aside from reducing glare and maintaining privacy, window shades are also useful in saving energy by aiding insulation and preventing energy dissipation. Shades should be installed close enough to the window panes to allow for a well-sealed airspace. Dual shades (which are highly reflective, or light-colored, on one side and are heat absorbing, or dark-colored, on the other) are even more energy efficient than most ordinary shades. The reflective side should always face the warmer side. The materials from which shades are made also affect their efficacy as means of insulation and light/air barrier; fiber batting controls the entry of air more effectively than other materials.