<P> The World Series is the annual championship series of Major League Baseball (MLB) and concludes the MLB postseason . First played in 1903, the World Series championship is determined through a best - of - seven playoff and is a contest between the champions of baseball's National League (NL) and American League (AL). Often referred to as the "Fall Classic", the modern World Series has been played every year since 1903 with two exceptions: in 1904, when the NL champion New York Giants declined to play the AL champion Boston Americans; and in 1994, when the series was canceled due to the players' strike . </P> <P> The best - of - seven style has been the format of all World Series except in 1903, 1919, 1920, and 1921, when the winner was determined through a best - of - nine playoff . Although the large majority of contests have been played entirely during the month of October, a small number of Series have also had games played during September and November . The Series - winning team is awarded the Commissioner's Trophy . Players, coaches, and others associated with the team are generally given World Series rings to commemorate their victory; however, they have received other items such as pocket watches and medallions in the past . The winning team is traditionally invited to the White House to meet the President of the United States . </P> <P> A total of 113 Series have been contested, with the NL champion winning 48 and the AL champion winning 65 . The New York Yankees of the AL have played in 40 World Series through 2017--winning 27--the most Series appearances, victories, and losses (13, shared with the Los Angeles Dodgers) of any Major League Baseball franchise . The St. Louis Cardinals, who represented the NL for a 19th time in 2013, have won 11 championships, which is the second-most among all 30 Major League Baseball teams as well as most among NL teams . Both the Giants and the Dodgers have been NL champions more times, with the Giants winning 23 NL pennants and the Dodgers winning 22 . </P> <P> The Seattle Mariners and the Washington Nationals (formerly Montreal Expos) are the only current Major League Baseball franchises to have never appeared in a World Series; the San Diego Padres, Colorado Rockies, Texas Rangers (formerly the 1961--1971 version of the Washington Senators), Tampa Bay Rays, and Milwaukee Brewers (formerly Seattle Pilots) have all played in the Series but have never won . The Toronto Blue Jays are the only franchise from outside the United States to appear in a World Series, winning in 1992 and 1993 . The current World Series champions are the Houston Astros . </P>

Who has played in the most world series games