Rules Reference

Definitions (runner) Definition of "runner"
5.05(a) (entire) The batter becomes a runner when …
5.05(a)(1) Batter hits a fair ball
5.05(a)(2) Third strike not caught
5.05(a)(3) Pitch bounces through strike zone, hits batter
5.05(a)(4) Batted ball touches umpire or runner
5.05(a)(5) Home run
5.05(a)(6, 7) Batted ball bounds out of play or lodges
5.05(a)(8) Bounding ball deflected out of play
5.05(a)(9) Fly ball deflected out of play
5.05(b) Batter awarded first base …
5.05(b)(1) Base on balls …
5.05(b)(2) Batter touched by pitched ball
5.05(b)(3) Batter interfered with
5.05(b)(4) Batted ball touched by umpire or runner - interference
5.06(a) Running the bases
5.06(a)(1) Runner's entitlement to a base, or forced to abandon
5.06(a)(2) Two runners on the same base
5.06(b) (entire) Advancing bases / Base awards
5.08(a, b) How a team scores
5.10(e) Courtesy runners not allowed