The “modern era” of baseball is typically considered to have begun in 1901, with the formation of the American League (AL) as a second major league in addition to the National League (NL). Prior to this, baseball had gone through a period of significant change and evolution, with the introduction of new rules, equipment, and playing styles.
The modern era is characterized by a number of important developments and changes in baseball, including the introduction of the designated hitter rule in the AL, the expansion of the league to include more teams and divisions, and the growth of the sport into a major cultural and economic force.
Other notable developments during the modern era of baseball include the introduction of night games, the rise of statistical analysis and sabermetrics, and the increasing influence of technology on the game, such as instant replay and digital scouting tools.
Overall, while the modern era of baseball has seen many changes and innovations, the basic elements of the game, such as hitting, pitching, and fielding, remain largely the same, and the spirit of competition and sportsmanship that defines the sport has remained a constant throughout its history.