A lot of people mistake the Euroleague for a real "league" like the NBA, where there's a fixed number of teams that face each other 2-5 times a year, then 16 teams reach the playoffs and battle for the championship. The Euroleague is actually more of a tournament. Here's the format:

REGULAR SEASON October 22, 2007 to Jan. 31, 2008

The Regular Season stage has 3 groups of 8 teams (a total of 24 teams). This is the first stage of the Euroleague.

Round Robin System with 14 games each club.
The Top 5 teams of each group plus the single
best sixth-placed team advance to the Top 16.

TOP 16 Feb. 13, 2007 to March 20, 2008

Unlike the NCAA's "Sweet 16", the Euroleague's "Top 16" is round robin. There are 4 groups of 4 teams (a total of 16 teams).

Round Robin System with 6 games each club.
The four group winners and the four second-place teams
in each group will advance to the 1/4 finals.


QUARTERFINALS April 1 to 10, 2008

The 1/4 finals isn't a one game elimination stage either. It's actually a best of three series.

Four best-of-three quarterfinal playoff series between
first and second-place finishers from the Top 16.
The four series winners advance to the Final Four.

FINAL FOUR in MADRID (Spain) May 2 to 4, 2008

The Final Four is THE event in European basketball. Like the NCAA's Final Four, it's one game elimination.

The four quarterfinals winners will meet in single-game semifinals.
The semifinals losers will play one game for third place.
The semifinals winners will play in the single-game Final.
The winner of the Final will be the Champion of the Euroleague.


RULES


The Euroleague's rules are very similiar to the NBA's rules, with a few exceptions:

-A game is 40 minutes long (4X10 minute quarters) instead of 48 minutes long.

-The three point line is a little closer (6.25 meters/20 ft 6 in from the basket) while the NBA three point line is 23 feet, 9 inches (7.23 m) from the basket.

-Holding the ball for 5 seconds without dribbling is a violation.

-The paint is smaller and is shaped like a trapazoid instead of a rectangle.

-There is no such thing as a "Defensive 3 Second" violation, which means a player can stand under the basket as long as he wants on defense.