The Calder Memorial Trophy is an annual award given "to the player selected as the most proficient in his first year of competition in the National Hockey League." The winner is selected in a poll of the Professional Hockey Writers Association at the end of the regular season; each voter ranks the top five candidates on a 10-7-5-3-1 points system. Three finalists are named and the trophy is awarded at the NHL Awards after the playoffs.
From 1936-37 until his death in 1943, NHL President Frank Calder bought a trophy each year to be given permanently to the outstanding rookie. After Calder's death, the NHL presented the Calder Memorial Trophy in his memory and the trophy is to be kept in perpetuity.
In 1990, 31-year-old Sergei Makarov of the Calgary Flames became the oldest player to win the Calder. Beginning with the 1990-91 season, the rules were amended so that players are eligible for the Calder only if they are no more than 26 years old by Sept. 15 of their rookie season.
To be eligible for the award, a player cannot have played more than 25 games in any single preceding season, nor in six or more games in each of any two preceding seasons, in any major professional league. That came into play 1979-80, when Wayne Gretzky was not eligible to win the Calder despite tying Marcel Dionne for the NHL scoring lead with 137 points (the previous rookie record at the time was 95), because he had played a full season in the World Hockey Association in 1978-79. The Toronto Maple Leafs lead all teams with 10 players who've won the Calder.