A scout is an observer sent to watch games and report on the performance of players he sees there. Major league teams use two types of scouts: talent scouts and advance scouts.
The scout most commonly thought of when using the term is a talent scout, who tries to identify players that his team may want to acquire. Teams operate large scouting networks to try to identify the best players. These networks have an elaborate hierarchy, with amateur "bird dogs" at the bottom and well-paid expert scouts at the top. A handful of great talent scouts - like Paul Krichell for the New York Yankees, Ira Thomas for the Philadelphia Athletics, and Cy Slapnicka for the Cleveland Indians- are known for being almost as important in building their teams as the managers.
A less well-known group are advance scouts, who gather intelligence on players their team will have to face. Advance scouts don't get the same publicity as talent scouts, but they can make important contributions to their teams' success. A rare famous case of advance scouting was by Howard Ehmke for the 1929 World Series. Both the Athletics and Cubs won their leagues by large margins, so Athletics manager Connie Mack knew his likely Series opponent with more than a month left in the season. Thus, Mack sent the old, sore-armed Ehmke to scout the Cubs and then made him a surprise starter in the first game of the Series. Armed with Ehmke's information, the Athletics were able to roll over the Cubs in 5 games, while Ehmke struck out a then-World Series record 13 Cubs en route to a complete game victory in Game 1.
Scouts have traditionally received little recognition for their work, which has been a standing complaint. The Hall of Fame tried to remedy that to some extent in 2013 by opening a permanent exhibit dedicated to their work at its baseball museum in Cooperstown, NY, entitled "Diamond Mines".
- Gib Bodet and P.J. Dragseth: Gib Bodet, Major League Scout: Twelve Thousand Baseball Games and Six Million Miles, McFarland, Jefferson, NC, 2014. ISBN 978-0-7864-7240-6
- P.J. Dragseth: Eye for Talent: Interviews with Veteran Baseball Scouts, McFarland, Jefferson, NC, 2010.
- P.J. Dragseth: Major League Baseball Scouts: A Biographical Dictionary, McFarland, Jefferson, NC, 2011.
- George Genovese and Dan Taylor: A Scout's Report: My 70 Years in Baseball, McFarland, Jefferson, NC, 2015. ISBN 978-0-7864-9730-0
- Kevin Kerrane: Dollar Sign on the Muscle: The World of Baseball Scouting, Bison Books, University of Nebraska Press, Lincoln, NE, 1999 (originally published in 1984).
- Lee Lowenfish: "Eyeball to Eyeball, Bellybutton to Bellybutton: Inside the Dodger Way of Scouting", in Jean Hastings Ardell and Andy McCue, ed.: Endless Seasons: Baseball in Southern California, The National Pastime, SABR, Number 41, 2011, pp. 97-100.
- Bob Nightengale: "For MLB scouts, it's getting harder to avoid force-out", USA Today Sports, January 14, 2016. 
- Art Stewart and Sam Mellinger: The Art of Scouting: Seven Decades Chasing Hopes and Dreams in Major League Baseball, Ascend Books, Olathe, KS, 2014. ISBN 978-0991275618
- Mark Winegardner: Prophet of the Sandlots: Journeys With a Major League Scout, Prentice Hall, New York, NY, 1990. ISBN 0-13-726373-2