W – Win | a pitcher receives a win when he is the pitcher of record when his team takes the lead for good — with a couple rare exceptions. First, a starting pitcher must pitch at least five innings (in a traditional game of nine innings or longer) to qualify for the win. If he does not, the official scorer awards the win to the most effective relief pitcher.

L – Loss | a pitcher receives a loss when a run that is charged to him proves to be the go-ahead run in the game, giving the opposing team a lead it never gives up.

ERA – Earned Run Average | represents the number of earned runs a pitcher allows per nine innings (or the length of the game of the category), with earned runs being any runs that scored without the aid of an error or a passed ball. 

APP – Appearance | a pitcher is credited with an appearance if he pitches in a given game. 

GS – Game Started | a pitcher is credited with a game started if he is the first pitcher to throw a pitch for his team in a given game. 

CG – Complete Game | a pitcher earns a complete game if he pitches the entire game for his team regardless of how long it lasts. 

SHO – Shutout | a starting pitcher is credited with a shutout when he pitches the entire game for a team and does not allow the opposition to score. 

IP – Innings Pitched | measures the number of innings a pitcher remains in a game. Because there are three outs in an inning, each out recorded represents one-third of an inning pitched. 

H – Hits | total hits allowed by pitcher.

R – Runs | the number of runs the pitcher has allowed, both earned and unearned. 

ER – Earned Runs | any run that scores against a pitcher without the benefit of an error or a passed ball. Often, it is the judgment of the official scorer as to whether a specific run would’ve scored without the defensive mishap.

BB – Base on Balls | refers to how many walks the pitcher has allowed. 

SO – Strike Out | occurs when a pitcher throws any combination of three swinging or looking strikes to a hitter. (A foul ball counts as a strike, but it cannot be the third and final strike of the at-bat. A foul tip, which is caught by the catcher, is considered a third strike.)

2B – Doubles Allowed | refers to how many doubles the pitcher has allowed.

3B – Triples Allowed | refers to how many triples the pitcher has allowed.

HR – Home Runs Allowed| refers to how many home runs the pitcher has allowed.

AB – At Bats Against | a count of the number of total at bats against a certain pitcher or team.

B/AVG – Opponent Batting Average | hits allowed divided by at-bats faced

WP – Wild Pitch | a pitcher is charged with a wild pitch when his pitch is so errant that the catcher is unable to control it and, as a result, baserunner(s) advance.

HBP – Hit by Pitch |times hit a batter with pitch, allowing runner to advance to first base.

BK – Balk | occurs when a pitcher makes an illegal motion on the mound that the umpire deems to be deceitful to the runner(s). As a result, any men on base are awarded the next base, and the pitch (if it was thrown in the first place) is waved off for a dead ball. 

SFA – Sacrifice Flies Allowed | refers to how many successful sacrifice flies the pitcher has allowed.

SHA – Sacrifice Hits Allowed | refers to how many successful bunts the pitcher has allowed. 

GO – Ground Outs | occurs when a batter hits a ball on the ground to a fielder, who records an out by throwing to or stepping on first base. It can also occur when the batter reaches first base — and the defence instead opts to record an out elsewhere via a “fielder’s choice.”

FO – Fly Outs | occurs when a batter hits the ball in the air and an opposing defender catches it before it hits the ground or fence.

NP – Number of Pitches | total number of pitches is determined by all the pitches he throws in live game action, including strikes, unintentional balls and intentional balls.