Short answers, pulled from the story.
A comeback occurs when an athlete or sports team overcomes a substantial disadvantage in points, position, or series. It has been described as the single greatest aspect of competition that most embodies the spirit of what makes sport extraordinary.
The Comeback refers to a specific NFL playoff game between the Buffalo Bills and Houston Oilers played the 3rd of January 1993. It featured the Bills recovering from a 32-point deficit shortly after halftime to win in overtime 41, 38.
Liverpool came back from a 3, 0 deficit in the first half after scoring three goals in 7 minutes to make it 3, 3 eventually winning the match 3, 2 on penalties during the 2005 UEFA Champions League final. The match was later dubbed The Miracle of Istanbul.
The greatest comeback in National Basketball Association play occurred on the 27th of November 1996 when the Utah Jazz down by 36 points to the Denver Nuggets late in the second quarter won 107, 103. Karl Malone scored 31 points and Jeff Hornacek contributed 29 points leading the victory according to Dustin Long's Greatest Comebacks in Sports published in 2014.
In ice hockey the largest single-game comeback in NHL playoff history happened the 10th of April 1982 when the Los Angeles Kings trailed the Edmonton Oilers 5, 0 going into the third period. The Kings rallied to score five unanswered goals winning the game 6, 5 in overtime on a goal by Daryl Evans.