Venetian blinds are a subcategory of the very similar Persian blinds. Like the latter, the slats are made of plastic or metal. Sometimes, wooden slats are incorporated. In the United States, though, this material would make them become referred to as wood blinds or sometimes as bamboo blinds. Unlike the Persian blinds, in which the slats are connected by string, Venetian blinds are connected by strips of cloth, and which are called tapes, or by cords. In both, the slats can be rotated almost 180°.
There are lift cords that pass through each slat. By pulling or lifting these cords, you can raise some or all of the slats, as the slats underneath the original, lifted slat are also raised. In this way, you can manually adjust how much light is shown, and where it is shown.
The history of Venetian blinds is somewhat unknown. The generally accepted originator of these blinds is England which documented it by making patents on it in the 1760s. However, the French knew about this much earlier. The most logical (due to its name) explanation is that the early Venetians, who were greatly skilled in trade, brought it over from Persia (and hence the similarity in features and appearance), and then shared it in France.
More recently, it has become known throughout the world. Radio City Music Hall and the Empire State Building used Venetian blinds throughout their buildings when they completed. The latter was very good news to the Burlington Venetian Blind Company of Burlington, Vermont which supplied the thousands and thousands of made to measure blinds.