The General Diet or Sejm (sejm walny) was the parliament of Poland from the 15th until the late 18th century. It was one of the primary elements of the democratic government of the Kingdom of Poland and, later, the Polish–Lithuanian Commonwealth. From the early 16th century, Polish kings could not pass laws without the Sejm's approval. Duration and frequency of Sejm sessions changed over time, with six-week sessions convened every two years being most common. Locations changed too, but eventually Warsaw emerged as the primary venue. The number of senators and deputies (members) grew over time, from about 70 senators and 50 deputies in the 15th century to about 150 senators and 200 deputies in the 18th. Early diets used majority voting, but beginning in the 17th century, unanimous voting became more common, with the liberum veto procedure significantly paralyzing the country's governance. It is estimated that between 1493 and 1793, 240 general diets were held. (Full article...)