77 articles
Henry Chadwick (writer)
Henry Chadwick (1824–1908), English-born American sportswriter called the Father of Baseball; invented the box score and 'K' for strikeouts, edited Beadle's and Spalding's guides, and was elected to the Hall of Fame in 1938.
Hit (baseball)
Hit (baseball): a batter reaches base on a batted ball in fair territory without an error or fielder's choice; four types (single, double, triple, home run), scored by the official scorer, and the basis of batting average.
Hitting for the cycle
Hitting for the cycle: one batter hits a single, double, triple, and home run in one game; also called a natural cycle when in order. About two per MLB year; record three career cycles by six players.
Hitting streak
A hitting streak in baseball is a run of consecutive games with at least one hit; Joe DiMaggio's 56-game streak in 1941 remains the MLB record.
Home run
Home run (HR): baseball play where the batter hits a fair ball and scores without being put out; also called homer, dinger, tater. Includes over-the-fence and rare inside-the-park versions, affected by park, wind, and temperature.
Infield fly rule
Infield fly rule, baseball rule (OBR 2.00, NCAA 2-48): batter is auto-out on an ordinary-effort infield popup with first and second or bases loaded, under two outs, preventing cheap double plays; enacted 1895.
Inside-the-park home run
Inside-the-park home run (IPH): a home run scored without the ball leaving the field, once common, now under 20 per MLB season; profiled by SABR since 1976.
Knuckle curve
Knuckle curve (KC), also called spike curve: a curveball gripped with the index-finger knuckle or nail on the ball. Curveball movement with added flutter; about 2% of MLB pitches; used by Kimbrel, Darvish, Brash.
Knuckleball
Knuckleball, a nearly spinless baseball pitch that flutters unpredictably; thrown with fingernails gripping the ball at 50-85 mph; used almost exclusively by rare specialists like Dickey, Niekro, and Wilhelm.
List of Major League Baseball career stolen bases leaders
MLB career stolen bases leaders list: Rickey Henderson holds the record with 1,406 steals (1979-2003), 468 ahead of Lou Brock's 938; covers rules history, top-10 rankings, success-rate thresholds, and 2023 rule-change effects.
List of Major League Baseball no-hitters
The list of Major League Baseball no-hitters covers 327 games in which pitchers allowed no hits over at least nine innings, a count MLB has maintained since 1991.
List of Major League Baseball perfect games
List of Major League Baseball perfect games: 24 official AL/NL perfect games, from Lee Richmond (June 12, 1880) through Domingo Germán (June 28, 2023); includes Don Larsen's lone World Series perfecto and rarity modeling.
List of Major League Baseball pitchers who have thrown an immaculate inning
Immaculate inning: three strikeouts on nine pitches in one inning. 123 recorded in MLB history as of 2026; none 1929-52; most (3) by Sale, Scherzer, Koufax; Astros first with two in one game (2022).
List of Major League Baseball players with a home run in their first major league at bat
This list covers the 146 Major League Baseball players who homered in their first big-league at bat, a feat first achieved by Mike Griffin and George Tebeau in 1887.
List of Major League Baseball retired numbers
List of Major League Baseball retired numbers: uniform numbers withdrawn by MLB clubs, beginning with Lou Gehrig's No. 4 (1939); Jackie Robinson's No. 42 is retired league-wide; the Yankees lead with 22 retired numbers.
Longest professional baseball game
Longest professional baseball game: Pawtucket Red Sox vs. Rochester Red Wings, Triple-A International League, McCoy Stadium, 1981; 33 innings, 8 hours 25 minutes, suspended at 2-2, Pawtucket won 3-2 on Dave Koza's single.
Major League Baseball tie-breaking procedures
MLB tie-breaking procedures: since 2022, standings ties are settled mathematically (head-to-head, intradivision, intraleague, last-half records) instead of by Game 163 tiebreaker games, which ended with the 12-team playoff expansion.
Manager (baseball)
Manager (baseball): the on-field strategic leader of a baseball team, historically called the captain; sets lineups, makes substitutions and pitching changes. Distinguished by uniform dress, rulebook substitution authority, the extinct player-manager role (last: Pete Rose, 1986), and mound-visit limits.
No-hitter
No-hitter: a baseball game in which a team gets no hits over at least nine innings. 326 in MLB history since 1876; record nine in 2021; 2025 had none, first since 2005. Distinct from a perfect game, which allows no baserunners.
Olly olly oxen free
Olly olly oxen free, also spelled Ollie ollie oxen free, is a catchphrase in children's games like hide and seek, shouted so out or hiding players can come in free.
On-base percentage
On-base percentage (OBP, OBA): baseball rate statistic, (H+BB+HBP)/(AB+BB+HBP+SF). Devised by Branch Rickey and Allan Roth; AL official 1979, NL 1984; records Bonds .609 (2004), Williams .482 career.
On-base plus slugging
On-base plus slugging (OPS) is a baseball stat equal to on-base percentage plus slugging percentage, devised by Pete Palmer; league average is about .700-.750, and OPS+ normalizes it to 100 with park and league adjustments.
Out (baseball)
Out (baseball): a batter or runner retired; the force out retires a runner by tagging the base he must advance to, removed when a trailing runner is forced out first, unlike tag outs and timing plays.
Perfect game (baseball)
Perfect game (baseball): retiring all 27 batters with none reaching base; 24 official MLB perfect games, first by Lee Richmond in 1880, most recent Domingo Germán in 2023, only postseason one by Don Larsen in 1956.
Pinch hitter
Pinch hitter (PH): a baseball substitute who bats in the replaced player's batting-order spot. First used 1889 (Mickey Welch); term coined 1896; Yogi Berra hit the first World Series pinch-hit homer in 1947.
Pine Tar Incident
The Pine Tar Incident, or Pine Tar Game, was the July 24, 1983 Yankees-Royals dispute in which George Brett's ninth-inning home run was overturned for excessive pine tar, then restored by AL President Lee MacPhail and completed August 18, 1983.
Pitch (baseball)
Pitch (baseball): the pitcher's throw to a batter from 60 feet 6 inches, judged against the strike zone; includes fastball, breaking ball, and offspeed types, Magnus-effect flight, and history from underhand 1845 rules to ABS.
Pitcher
Pitcher: the baseball defensive player who delivers pitches to the batter. Covers delivery mechanics, 14 Statcast pitch types, starter/reliever/opener roles, pitch-timer rules, and UCL injury research, distinguishing baseball from softball's windmill pitch.
Rules of baseball
Rules of baseball: the codified playing rules, chiefly MLB's Official Baseball Rules, plus WBSC, NCAA, and NFHS codes. Covers strike zone, infield fly, balks, 2023 pitch-clock and shift changes, and ABS adoption for 2026.
Run (baseball)
Run (baseball): the unit of scoring, credited when a player legally touches home plate. Covers run scored, earned vs. unearned runs, RBI, Rule 5.08, and run-estimation metrics like Runs Created and BaseRuns.