A double-double is a basketball term, defined as an individual performance in a game in which a player accumulates a double digit number total in any two of these categories: points, rebounds, assists, steals, and blocked shots.
Double-doubles, unlike the more difficult triple-doubles (or ultra-rare quadruple-doubles), are very common in the NBA, and in fact there is usually at least one player in each NBA game that manages to record one. In each NBA season, rarely more than a handful of players average a double-double; in the 2003-04 NBA season, only 9 players were able to accomplish that feat, each averaging more than 10 points and 10 rebounds per game.