There are two different types of professional baseball in the U.S. -- Major League Baseball (MLB) and its affiliated Minor League Baseball system, and independent league or non-affiliated MLB of which there are seven leagues. There are also thousands of U.S. amateur high school and college teams.
MLB and Minor League Baseball overview: Comprised of 30 teams separated in two leagues. The American League, founded in 1901, features 14 teams while the National League, founded in 1876, has 16 teams. Each club plays a 162-game regular season schedule from April through September, with only a small number of those games against teams in the opposing league. The three division winners from each league, plus a fourth team with the next best overall record, known as a "wild card," advance to the playoffs. The first round playoff, a best-of-five, determines the two teams left to compete for their respective league titles in a best-of-seven series. Since 1903, the best team from each league then competes in the "World Series," which today is a best-of-seven series. More than 30 percent of the players in MLB were born outside the U.S. and there are no rules regarding the number of foreign-born players that may be on a particular team. The American League employs the designated hitter while the pitcher must bat in National League games. Each of the 30 MLB teams also boasts a minimum of six, affiliated Minor League clubs, playing at various levels, scattered throughout the U.S., Canada, Mexico, as well as in the Dominican Republic and Venezuela. Whether a player is drafted or signed as a free agent by an MLB organization, the vast majority begin their career in the minor leagues and then work there way up to MLB.
Most successful MLB franchise: The New York Yankees have won 26 World Series titles.
Biggest MLB rivalries: Red Sox-Yankees; Giants-Dodgers; Cubs-Cardinals.
Best MLB ballparks: Only two of MLB's current ballparks debuted before 1960 and they are considered the game's remaining shrines: The Boston Red Sox Fenway Park (1912) and the Chicago Cubs Wrigley Field (1914).
Ballpark food and drink: American fare such as the hot dog, popcorn, soda pop and beer have been joined in the past decade by international cuisine, reflective of the infusion of foreign-born players into MLB and America's melting pot of cultures. For example, in Seattle, home of the Mariners, fans can purchase an "Ichiro Roll," in honor of Japanese star, Ichiro Suzuki. More sophisticated food and drink is also available, include wine.
Ballpark atmosphere: MLB's two oldest ballparks are also home to the game's best atmosphere. Fenway Park is known for its rabid fans, known as "Red Sox Nation" that sell out every game. Wrigley Field, nicknamed "The Friendly Confines," is known for its famous bleachers and 7th inning stretch in which an announcer will lead fans in song (for more info, see "Unique Traditions" below). Yankee Stadium, known as "The House that Ruth Built," has traditionally been notable for its public address announcer Bob Sheppard, known to some as the "Voice of God," who has been introducing Yankees for more than a half-century. The stadium is also known for its thunderous noise during the first inning, dubbed "Roll Call," and its tribute to former Yankees players in Monument Park beyond the outfield fence (before the game, fans can walk through the park to enjoy plaques and more of the likes of Babe Ruth and others).
Wildest mascots: "The Philly Phanatic" is a nearly 30-year-old mascot for the Philadelphia Phillies that came to power after "The San Diego Chicken" rose to prominence in the 1970s working for the San Diego Padres. Both mascots remain as popular today as ever, although the Chicken is not the Padres official mascot.
American baseball speak: "The Show" is a common phrase U.S. ballplayers share in the minor leagues. When one of their peers gets called up to MLB, he's finally made it to "The Show."
Unique traditions: The 7th inning stretch is a unique MLB tradition in which fans stand up together, loosely stretch and sing "Take me out to the ballgame." It takes place after the visiting team has finishing batting in the top of the seventh inning and begins when the public address announcer prompts fans with "It is seventh inning stretch time!" The origins of this tradition are murky but they were incorporated into professional baseball in the 1880s. In 1882, a Manhattan College coach, noticing restless fans on a hot, muggy day, encouraged them to stand up and unwind during the seventh inning. The New York Giants tried the approach during an exhibition game and the rest is history Every summer, at the halfway point of the regular season, an All-Star Game featuring the best players from the two leagues takes place on the second Tuesday evening in July. The league that wins the game receives home-field advantage in the best-of-seven World Series. The site of each All-Star Game is determined by the MLB commissioner, and often rotates between the leagues.
Joe Connor is a contributor to ESPN.com who has visited more than 30 baseball countries on six continents. He's the author of "A Fan's Guide To The World Baseball Classic," which is available for purchase exclusively at his Web sites: www.modernerabaseball.com and www.mrsportstravel.com.