Lynn Nolan Ryan Jr. (born January 31, 1947), nicknamed "the Ryan Express", is an American former professional baseball pitcher and sports executive. Over a record 27-year playing career in Major League Baseball (MLB) spanning four decades, Ryan pitched for the New York Mets, California Angels, Houston Astros, and Texas Rangers. After his retirement in 1993, Ryan served as chief executive officer (CEO) of the Texas Rangers and an executive advisor to the Houston Astros. He was inducted into the Baseball Hall of Fame in 1999, and is widely considered to be one of the best MLB pitchers of all time.

Ryan was a right-handed pitcher who consistently threw pitches that were clocked above 100 miles per hour (161 km/h). He maintained this velocity throughout his pitching career. Ryan was also known to throw a devastating 126 curveball at exceptional velocity for a breaking ball.Ryan had a lifetime winloss record of 324292 (.526) and was an eight-time All-Star. His 5,714 career strikeouts is an MLB record by a significant margin. He leads the runner-up, Randy Johnson, by 839 strikeouts. Similarly, Ryan's 2,795 bases on balls lead second-place Steve Carlton by 962 walking over 50% more hitters than any other pitcher in MLB history. Ryan's lifetime batting average against of .204 is also a major league record. Ryan, Pedro Martnez, Randy Johnson, Trevor Hoffman, and Sandy Koufax are the only five pitchers inducted into the Baseball Hall of Fame who had more strikeouts than innings pitched. Ryan is one of only three players in history to have his number retired by at least three teams, along with Jackie Robinson (whose number was retired by Major League Baseball) and Frank Robinson.

Ryan is the all-time leader in no-hitters with seven, three more than any other pitcher. He is tied with Bob Feller for the most one-hitters, with 12. Ryan also pitched 18 two-hitters. Despite this, he never pitched a perfect game, nor did he ever win a Cy Young Award. Ryan is one of only 29 players in baseball history to have appeared in MLB games in four different decades.

Baseball is a bat-and-ball game played between two opposing teams, of nine players each, that take turns batting and fielding. The game proceeds when a player on the fielding team, called the pitcher, throws a ball which a player on the batting team tries to hit with a bat. The objective of the offensive team (batting team) is to hit the ball into the field of play, allowing its players to run the bases, having them advance counter-clockwise around four bases to score what are called "runs". The objective of the defensive team (fielding team) is to prevent batters from becoming runners, and to prevent runners' advance around the bases. A run is scored when a runner legally advances around the bases in order and touches home plate (the place where the player started as a batter). The team that scores the most runs by the end of the game is the winner.

The first objective of the batting team is to have a player reach first base safely. A player on the batting team who reaches first base without being called "out" can attempt to advance to subsequent bases as a runner, either immediately or during teammates' turns batting. The fielding team tries to prevent runs by getting batters or runners "out", which forces them out of the field of play. Both the pitcher and fielders have methods of getting the batting team's players out. The opposing teams switch back and forth between batting and fielding; the batting team's turn to bat is over once the fielding team records three outs. One turn batting for each team constitutes an inning. A game is usually composed of nine innings, and the team with the greater number of runs at the end of the game wins. If scores are tied at the end of nine innings, extra innings are usually played. Baseball has no game clock, although most games end in the ninth inning.

Baseball evolved from older bat-and-ball games already being played in England by the mid-18th century. This game was brought by immigrants to North America, where the modern version developed. By the late 19th century, baseball was widely recognized as the national sport of the United States. Baseball is popular in North America and parts of Central and South America, the Caribbean, and East Asia, particularly in Japan, South Korea, and Taiwan.

In the United States and Canada, professional Major League Baseball (MLB) teams are divided into the National League (NL) and American League (AL), each with three divisions: East, West, and Central. The MLB champion is determined by playoffs that culminate in the World Series. The top level of play is similarly split in Japan between the Central and Pacific Leagues and in Cuba between the West League and East League. The World Baseball Classic, organized by the World Baseball Softball Confederation, is the major international competition of the sport and attracts the top national teams from around the world.