If you are not familiar with Major League Baseball and watch or attend a game on April 15, you might be confused as to why every player is wearing the No. 42. And no, it’s not because every player has the same number.

Born Jan. 31, 1919, Jack Roosevelt Robinson was raised in relative poverty by his single mother in Cairo, Georgia.

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He later enrolled at UCLA — where he played baseball, football, basketball and ran track — becoming the first student to earn varsity letters in four different sports.

From 1942 to 1944, Robinson’s athletic career was temporarily put on hold when he served as a second lieutenant in the United States Army during World War II. His refusal to give up his seat and go to the back of a segregated bus during boot camp at Fort Hood, Texas, resulted in his detention in 1944. This incident served as a prelude to his later-life advocacy and acts of sacrifice.

In 1944, following his release from the Army, Robinson started playing baseball professionally.  He started his career with the Kansas City Monarchs in the Negro Leagues, but Brooklyn Dodgers president Branch Rickey quickly signed him to break the social color barrier within the sport.

On April 15, 1947, Robinson took the field for the Brooklyn Dodgers in his first game, becoming the first Black athlete to compete in the MLB. Each year since 2004, every MLB player has worn No. 42 on April 15 to honor Robinson and the historical event of the color barrier being broken.

From that day on, Robinson faced intense discrimination as a member of the Dodgers organization. In the minors, he had a fantastic start with the Royals despite the racist taunts, specifically while they were playing in ballparks away from home.

Unfortunately, the majors were still the scene of harassment for Robinson. Being a Black American on the team infuriated some of his new teammates. So much so that some of them threatened to strike if Robinson remained on the team. Furthermore, threats were made against him and his family, and Robinson continued to be the target of slurs from the crowd and opposing teams.

The most noteworthy instance of this came in a game during the 1947 season from Philadelphia Phillies manager Ben Chapman. From his dugout, Chapman yelled derogatory phrases at Robinson in an attempt to get under his skin.

Despite all of the racism he faced on and off the field, Robinson managed to muster up a Hall of Fame career. Over the course of his 10-year stint in “The Show,” he posted an impressive .313 average over 4,997 at-bats. The Georgia native also tallied 141 home runs, 1,563 hits, 761 runs batted-in, 200 stolen bases, a .410 on-base percentage and a .477 slugging percentage. Additionally, with his daredevil decision making and cat-like reflexes, Robinson successfully stole home 19 times in his career, tied for ninth all-time.

In terms of accolades, in addition to winning the World Series in 1955, he was voted Rookie of the Year in 1947 and the National League Most Valuable Player in 1949.

Breaking the color barrier would have sufficed in and of itself, but Robinson contributed much more off the field to distinguish himself as one of the most influential athletes of all time.

Until 1967, Robinson was on the board of the National Association for the Advancement of Colored People and was a vocal supporter of Black athletes, civil rights, and other social and political concerns. For example, he gave a testimony regarding prejudice before the House Un-American Activities Committee in July 1949.

In 1952, five years after he started playing for the Dodgers, he publicly denounced the New York Yankees as a racist team for not having broken the color barrier. Robinson persisted in advocating for further racial integration in sports into his older years.

On Aug. 28, 1963, Robinson attended the March on Washington for Jobs and Freedom, where his good friend Martin Luther King Jr. gave his famous “I Have a Dream” speech. To raise money for King’s bail as well as the bail of other activists detained during rallies, Robinson and his spouse, Rachel, hosted jazz concerts at their residence.

Robinson continued to fight for justice until he tragically passed away on Oct. 24, 1972 in Connecticut at the age of just 53. He will forever be remembered for his impact on baseball and social activism.

So, on April 15 this year — whether you are watching a baseball game or not — take a second to appreciate Jackie Robinson and all he has done for Black athletes, the MLB and athletics as a whole.

Joshua Sacher is a sophomore writing about athletes who led the change for social justice in his column, “More Than An Athlete,” which runs every other Thursday. He is also a sports editor at the Daily Trojan.