Venetian blinds are a type of window covering, nearly always found on the inside of the window. They serve the purpose of blocking out external light (hence the name blind), as well as hiding the inside of the structure from exterior viewing.
Venetian blinds are slatted blinds, consisting of a number of long horizontal strips attached in rows. In the modern world Venetian blinds are nearly always made of metal or wood, but these are now referred to as wooden blinds.
The slats are usually connected with string such that they may be turned to either allow light to pass through them by becoming parallel with the window-sill, or else turned flat to block light from the outside. Usually the turning of the slats is accomplished by rotating a metal or plastic piece found at the upper-corner of the blinds. A string or pull allows the blinds to be raised, as well, removing them entirely from obscuring the window.