From BR Bullpen
A Boxscore or Box score is a summary of a baseball game written in a table form. There are two main types of boxscores: the newspaper boxscore and the official boxscore.
The format of the newspaper boxscore is determined by the traditional division of a newspaper page into columns. As a result, the boxscore can only convey a limited amount of information, often in abbreviated form. The official boxscore is prepared by the official scorer and contains much more information, including defensive statistics, a full explanation of substitutions, and other data as mandated under section 10.02 and 10.03 of the MLB rules . The boxscores published by Retrosheet are the official ones.
 How to decipher a boxscore
 The line score
The first few lines of a typical newspaper boxscore would read something like this:
|Metropolis 3||Gotham 2|
In this case, Metropolis has won the game over Gotham by a score of 3 to 2. The two lines of numbers below are the "line score". Each number before the hyphen corresponds to the number of runs scored in a specific inning. Here, Gotham scored one run in the first inning and one in the sixth, while Metropolis scored two in the fourth and one in its half of the sixth. The "x" for Metropolis in the ninth inning indicates that the team did not bat that half inning, as the game was already won. The numbers after the hyphen indicate the runs scored, base hits and errors for each team. Gotham scored two runs on five hits and committed two errors, while Metropolis scored its three runs on eight hits and did not make an error.
 The line-ups
Following the line score is a list of names that would look like this:
Gotham was the visiting team, therefore its line-up is listed first after the line score. Its batting order began with shortstop A. Smith, left fielder L. Jones and center fielder Anderson (no initial listed because he was likely the only Anderson in the league). "Mrtnsn" was a pinch hitter for Anderson, who then went to play first base on defense. Notice that unless we know who the player is, it is impossible to know whether this refers to someone named Martinson, Mortensen or another similar last name. The restricted column space forces the use of such compressed names, which can lead to confusion. Substitutes are listed after the players that they replaced, and not in the order they entered the game. Therefore, a bit of deduction is required to reconstitute the original starting line-up.
The names are followed by position indicators: p: pitcher; c: catcher; 1b: first baseman; 2b: second baseman; 3b: third baseman; ss: shortstop; lf: left fielder; cf: center fielder; rf: right fielder; dh: designated hitter; ph: pinch hitter; and pr: pinch runner) A hyphen or a coma between two abbreviations means that the player played both positions, in the order listed.
The numbers following the position designation refer respectively to at bats, runs scored, hits and RBIs. Note that bases on balls are not indicated and must be infered from other available information. For example, Jones had only three at-bats, but should have four plate appearances at least, since the third spot in the order has four at-bats. The missing plate appearance can be either a base on balls, a sacrifice or a hit by pitch.
After the two complete line-ups are listed with the four hitting statistics, there are a number of additional lines of text, along this format:
|E: Martinez 2; DP: Met 1; 2B: none;|
|3B: ASmith; HR: Lewis 2 (13),|
|Hellmann (3); Sac: Lenzer; SF: LJones|
The "E" stands for errors, and indicates that Martinez committed two of them in the game. "DP" is Double play; Metropolis turned one. "2B", "3B" and "HR" are doubles, triples and home runs, followed by the names of the players who hit them, how many if more than one (Lewis hit two home runs) and for home runs, the number that the players have hit this season (for Lewis, the two shots were his 12th and 13th of the year, while Hellmann hit his third). Notice that the players' teams are not listed in this section, as the information can be gathered from the line-ups above. "Sac" refers to sacrifice hits, and "SF" to sacrifice flies.
We already have enough information to reconstitute Gotham's first inning. We know that the team scored one run, which must have been scored by one of the first three batters. Since only lead-off man Smith has a run credited to him, it must be him. How did he reach base ? Most likely via his one hit, which we know was a triple. Who drove him in ? We see that the second batter, Jones, has one run batted in without the benefit of a hit, and is credited with a sacrifice fly. This is how the run likely scored, and explains Jones's missing plate appearance (as a sacrifice fly does not count as an at-bat). In most cases, it is not possible to reconstitute the exact play-by-play from a boxscore only.
 The pitching summary
The next section of the boxscore is the pitching summary. It would look something like this:
|Armando faced three batters in the sixth|
This section lists the names of all the pitchers who took part in the game, in order of appearance. For Gotham, starting pitcher Armando pitched five innings and was saddled with the loss (bringing his record for the season to 4 wins and 5 losses). The note underneath mentions that he actually pitched into the sixth inning, but was relieved after facing three batters but retiring none of them. The second number is the hits allowed, followed by runs allowed, earned runs, bases on balls and strikeouts. The "2.1" for Nichols means that he pitched two innings and a third. In this game, he would have completed the sixth inning after Armando's departure, pitched the seventh inning, and been removed after one out in the eighth. For Metropolis, Lenzer pitched a complete game and was credited with the win. We can also see that one of the runs allowed by Armando was unearned, likely as a result of one or both of the errors by Martinez.
Other pitching statistics are listed below the pitching lines. These would include "WP" for wild pitch, "Bk" for a balk, "PB" for a passed ball (charged to the catcher, not to the pitcher), "HBP" for a hit batsman, which would be noted HBP: SGarcia (by Nichols), for example, with Nichols the pitcher and S. Garcia the batter who took one for the team.
 Evolution of the Boxscore
The first boxscore was printed by the New York Morning News on October 22, 1845. It was based on the box scores, or abstracts, used to describe cricket games. The listing of players in two columns, according to batting order, is similar to the format used today, but the only information captured about each player was the number of outs made and runs scored.
By the next decade, boxscores had started to expand to include information such as at bats and hits, as well as columns for putouts and assists. The line score appeared by the end of the 19th Century, but full pitching lines would not be commonly included until the 1950's. The RBI was introduced in the 1920's, while defensive statistics were removed a few decades later, as a space-saving measure, and are still rarely found outside official boxscores to this day.
In current times, the classical newspaper boxscore is becoming increasingly rare, as the newspapers that choose to publish boxscores usually include a lot of additional information, such as bases on balls, strikeouts, batting averages, pitch counts and ERAs, reflecting the interest of sabermetrically-inclined readers and fantasy baseball players. Boxscores are also largely available on-line these days, where space limitations are not much of a concern, and much more detailed information can be included.
 Further Reading
- Alan Schwarz: "Take Me Out to the Box Score", The New York Times, April 2, 2006, p. BB2.