Bomb

Bombs were weapons available since the Middle Ages.

History
Smoke Bombs were the only type of bombs that were commonly available to Ezio up until the 16th century; when he travelled to Constantinople, he had a far more extensive choice of bombs.

12th century
Altaïr had access to smoke bombs during his quest for the Chalice and used them in generally the same way as Ezio Auditore used them, and he could carry up to five of them. He seemed to not use them anymore after the events at Solomon's Temple.

15th century
Smoke Bombs were disposable and had to be purchased for 350 florins each. Ezio could carry a maximum of three Smoke Bombs at a time, which were stored in a non-upgradeable pouch.

16th century
Smoke bombs returned when in Rome, with the same abilities as before, though the actual cloud itself was visually a lot smaller than during the previous century. Smoke Bombs were also used by Assassin recruits once they reached the rank of Veterano (Veteran). Ezio could also use Smoke Bombs during his visit to Constantinople.

Technique
Using a powder technology from the Far East, the bomb releases a thick, grayish smoke screen for 8 seconds when thrown, to allow Ezio Auditore to flee his enemies, or assassinate them quickly within those seconds. The clever and strategic use of Smoke Bombs during difficult assassinations or large guard fights was very important, as they allowed Assassins to strike specific targets or take down larger groups of enemies without being seen or encountering resistance, and allowed them to slip in and out of hotspots undetected.

Hand-held bombs
"Quite little bombs, but effective enough to, say, wreck ships or disperse a camp."

- Leonardo da Vinci.

Hand-held bombs were small explosive devices designed and manufactured by Leonardo da Vinci. Consisting of a small, steel ball filled with sulfur, charcoal and potassium nitrate, they also possessed a small fuse which required lighting before the device could be detonated.

History
The bombs were first used against Cesare Borgia's diehards, who had amassed a sizable military force in the city of Valencia.

During the attack on Valencia, Ezio and Niccolò Machiavelli, each equipped with ten hand-held bombs, brought chaos to Cesare's military forces. They destroyed twelve Borgia ships, and an entire military encampment.

Upon traveling to Constantinople, Ezio crafted and used a variety of other bombs, similar to those made by Leonardo. The known types of bombs used by Ezio during his search for the Seals were Tripwire Bombs, Smoke Bombs and Fire Crackers.

Trivia

 * In Assassin's Creed II, the Smoke Bomb pouch is labelled as "small" despite not having any upgrades.
 * In Assassin's Creed II, in the memory "Cheaters Never Prosper," the three guards and Dante Moro are immune to Smoke Bombs.
 * While looting Brutes, there is a high chance of obtaining some Smoke Bombs.
 * In Brotherhood, there seems to be a small spark of light when a Smoke Bomb is being deployed, unlike in Assassin's Creed II, where there is no spark.AC_Brotherhood_icon_Smoke_Bomb.png
 * In Assassin's Creed II, Smoke Bombs are very helpful for earning the achievements/trophies "No Hitter", "Messer Sandman", and "Sweeper".
 * In Brotherhood, one of the BAM (Brotherhood Assist Move) maneuvers has the Assassins throw numerous Smoke Bombs around Ezio before descending to aid him.
 * In Brotherhood, the player may lock onto a far-off NPC before pressing the "throw bomb" button to throw the Smoke Bomb from a distance.
 * In Brotherhood, Papal guards are immune to the effects of Smoke Bombs if not taken by surprise, i.e. in combat.
 * The Smoke Bomb also appear in the Brotherhood multiplayer mode as an ability.
 * In Brotherhood, Cesare Borgia is completely immune to Smoke Bombs.
 * In Brotherhood, pickpockets are completely immune to Smoke Bombs.
 * In Assassin's Creed: Revelations, the only way to see through the smoke of the Smoke Bomb is to turn on Eagle Sense.