The Smart Bomb (スマートボム,Sumāto Bomu?), sometimes called the "B-bomb" for the large B on its front, is an item in Super Smash Bros. Brawl. It is one of the most powerful thrown items in the game. Once it hits an opponent, travels a certain distance, or gets attacked, it produces a large, slow explosion that envelops a big range and damages everyone inside in increments of 1% for about three seconds. Characters caught in the blast can shift their position using smash DI, but usually cannot escape until the explosion ends and flings them away. (Escape is possible with smash DI as seen here:  at 0:16.) The bomb does a great deal of damage but generally does not KO.
There is a small chance that a Smart Bomb will turn out to not explode; instead of going off it makes a distinctive echoing noise and travels through its target, causing flinching but no knockback. A dud Smart Bomb will still explode when attacked and may explode at a random time, even when picked up again. One can use Fox Illusion or any projectile to safely activate a Smart Bomb while the opponent is distracted.
A bomb that explodes and causes damage to all characters within its range when thrown or attacked. The explosion from this device is so large, the deployer may be caught in the blast if he or she is not careful. In Star Fox, this item will explode after a set time or can be set off immediately with a button press.
The Smart Bomb comes from the Star Fox series. It was originally named the Nova Bomb. In Star Fox 64, it could either be locked on to opponents or triggered to explode after launch by pressing the button a second time. It also would explode on impact, or after it traveled a certain distance. It did not hurt Fox or his wingmen.
If there are lots of enemies in an area and multiple Smart Bombs go off at once, the game may lag.
If one detonates on one of Snake's mines, the mine explodes rapidly until the Smart Bomb ends.
In training mode, if five Smart Bombs (the most it's possible to have out at any one time) are placed near an opponent and detonated all at once, as well as dealing up to around 160% damage to the opponent, it is possible to get a sixty-hit combo, and, if you keep spawning them over and over, it is possible to reach a 999-hit combo.
In Kirby Air Ride, the bomb that characters can throw has similar effects as the Smart Bombs have in Super Smash Bros. Brawl.