Leap of Faith

The Leap of Faith was an acrobatic move in which the person performing it dove from atop a high structure to land, unharmed, in a conveniently placed pile of hay or other soft landing material. It was integral for the members of the Assassin Order, and served as a requirement for their initiation.

Description
The acrobatic move itself consisted of a vertical leap, with back completely straight, followed by a body-roll in mid-air to allow the one performing it to land on his or her back.

Leaps of Faith could be performed by Free Running off any high ledge or beam. Areas from which a Leap could be performed were often marked by bird droppings, and pigeons perched upon the ledge.

Third Crusade
The Leap of Faith was used to descend from View Points, each of which always provided a suitable safe target for it. However, it could be used to jump down from anywhere, if, of course, there was a safe target below.

It was also handy in losing pursuing guards on rooftops, as leaping down to street level automatically caused the Assassin to leave the pursuers' line of sight.

Renaissance
Though Altaïr Ibn-La'Ahad only performed Leaps of Faith into piles of hay, Ezio Auditore could make use of water and other piles of soft material; such as piles of leaves or flower petals.

Upon traveling to Rome, Ezio made use of the Leap of Faith to quickly escape the Borgia Towers he climbed and set aflame.

As per tradition, Ezio also required each of his Assassin recruits to perform a Leap of Faith from the top of the Tiber Island hideout, into the Tiber River below.

Modern Times
Desmond Miles performed his first Leap of Faith in the run-down, modern Monteriggioni, after witnessing (thanks to the bleeding effect) Ezio climbing up to a View Point.

Additionally, at Abstergo Industries, several Abstergo recruits also performed Leaps of Faith, through the simulations they participated in, within the Animus training program.

Assassin's Creed

 * Near the beginning of the game, when Masyaf is attacked by Templars, three Assassins display their devotion by performing Leaps of Faith from a cliff. This is based on a real life incident involving the Hashshashin, in which their leader proclaimed that his followers were more devout than any, and would follow all commands he gave. As shown in the game, he ordered several men to jump from a cliff "to their deaths," which they did.
 * The incident is also depicted in the novel Alamut, by Vladimir Bartol; though only one man leaps from a tower, while another kills himself with a dagger.
 * There is actually nothing coincidental about the placement of the piles of hay. It is explained that the bales of hay and the birds that denote the location of a View Point have been programmed into the memory by Lucy Stillman, as a way to help out in the navigation of the memory.

Assassin's Creed II

 * When being pursued by Ezio, Francesco de' Pazzi leaps off the Palazzo della Signoria into a haystack for a quick escape. This was the only known example for a non-Assassin committing a form of a Leap of Faith until Assassin's Creed: Brotherhood.
 * To achieve the "High Dive" achievement, you must perform a Leap of Faith from Giotto's Campanile in Florence, as it is the highest viewpoint in the game.
 * Ezio can perform an alternative leap of faith by hanging from a ledge or View Point and falling backwards onto a safe spot, as long as he is high enough and/or the safe spot is directly below him. He is forced to do this at least once, after speaking with his father during the "Jailbird" memory.

Others

 * In reality, it is unlikely that a haystack in a cart would be able to safely cushion someone falling from a great height. The momentum may also cause the cart to collapse.
 * It is suggested in Assassin's Creed: Brotherhood that very few of the modern-age Assassins perform the Leap of Faith, due to Lucy Stillman saying it was "pretty awesome" when she witnesses Desmond Miles performing his first-ever Leap. It should be noted that Lucy does not perform the Leap herself, and instead takes a ladder down the cliff to follow Desmond.
 * As an easter egg in Metal Gear Solid: Peace Walker, Big Boss (and the soldiers he has recruited) can perform Leaps of Faith into straw boxes called "Assassin Straw Box."
 * In assassins creed 2 discovery you can do a backwards leap of faith,by facing the oposite way of the hiding spot(unless an alley way)and ezio will flip 3 times.