Win Shares is a baseball statistic that estimates a player's contribution to their team's wins. It combines a player's offensive and defensive performance into a single number, making it easier to compare players across different positions and eras. The concept was developed by Bill James, a prominent baseball statistician. Each player is assigned a certain number of Win Shares based on their performance metrics, such as batting average, on-base percentage, and fielding statistics. This metric helps fans and analysts understand a player's overall impact on their team's success, providing a clearer picture of their value in the game.