The Boston Celtics are an American professional basketball team based in Boston, Massachusetts. The Celtics compete in the National Basketball Association (NBA) as a member of the league's Eastern Conference Atlantic Division. Founded in 1946 as one of the original eight NBA teams to survive the league's first decade, the team is owned by Boston Basketball Partners LLC. The Celtics play their home games at the TD Garden, which they share with the National Hockey League (NHL)'s Boston Bruins. The franchise is the most successful in NBA history, with 17 championships, which accounts for 23.9 percent of all NBA championships since the league's founding.The Celtics have a notable rivalry with the Los Angeles Lakers, and have played the Lakers a record 12 times in the NBA Finals (including their most recent appearances in 2008 and 2010), of which the Celtics have won 9. Four Celtics players (Bob Cousy, Bill Russell, Dave Cowens and Larry Bird) have won the NBA Most Valuable Player Award for an NBA record total of 10 MVP awards. Both the nickname "Celtics" and their mascot "Lucky the Leprechaun" are a nod to Boston's historically large Irish population.After winning 16 championships throughout the 20th century, the Celtics, after struggling through the 1990s, rose again to win a championship in 2008 with the help of Kevin Garnett, Paul Pierce, and Ray Allen in what was known as the new "Big Three" era, following the original "Big Three" era that featured Larry Bird, Kevin McHale, and Robert Parish, which combined to win the 1981, 1984, and 1986 championships.
Following the win in 2008, general manager Danny Ainge began a rebuilding process with the help of head coach Brad Stevens, who led the Celtics to a return to the playoffs from 2015. During the following season, the Celtics clinched the top seed in the Eastern Conference, and eventually reached the Conference Finals prior to losing to the Cleveland Cavaliers in five games.
In the 2017 off-season, via some trades and free agency, Ainge rebuilt the roster into a championship caliber team after signing Kyrie Irving and Gordon Hayward. During the season opener, Hayward left the game with a season-ending injury by dislocating his ankle and fracturing his tibia. Irving went down in March and went through knee surgery. By the end of the season, the Celtics finished second in the Eastern Conference standings. Nevertheless, they entered the playoffs and managed to reach the Eastern Conference Finals, taking the Cavaliers to seven games. The Celtics lost game seven, eliminating them from the playoffs.