Twenty-six years have passed since the original edition of The Official Rules of Baseball Illustrated first appeared in 1994. In that time several baseball historians and researchers have imparted information that has been of considerable help in preparing the 2020 edition. The author would especially like to thank his editor, Jason Katzman, and fellow baseball historians and researchers Dennis Bingham, Rich Topp, Bill Deane, Ev Cope, Frank Vaccaro, John Thorn, David Ball, Dick Thompson, Al Blumkin, Pete Palmer, Don Malcolm, Dave Zeman, David N. Johnson, Stew Thornley, Ken Samelson, Bob Tiemann, Cappy Gagnon, Richard Malatzky, and Richard Hershberger for their invaluable contributions, along with Eric Miklich and Scott Flatow for fact-checking much of the updated material with their usual expert eyes.