Engram

"The unique datastatic structure of relic crystals inspired Doctor Willa Bray to develop the first engram matter-encryption techniques during the Golden Age."

- Ghost Engrams are crystals that are encoded with the patterns of armor, weaponry and other items. There are five basic types of Engrams: Encoded, Encrypted, Decoherent, Legendary, and Exotic.

History
Engrams are a unique, "pure" state of matter, the form solid matter takes when physically encrypted. First successfully generated by Willa Bray, Clovis Bray proceeded to head the field of engram research and application.

Engrams were often used to store information, such as manuscripts or research. They were known to degrade over time. Engrams dating from the Golden Age were normally mostly illegible.

One of the most significant applications of engrams is for computing. By the end of the 21st century, computer engineers had reached the physical limits of transistor-based computing, unable to overcome quantum incoherence at the nanoscopic level. This halted research for some time. However, engram encryption allowed quantum incoherence to be bypassed: transistors encoded into engrams could store exponentially more information in a smaller space. The discovery of engrammic computation, one of Clovis Bray's last developments before the Collapse, led to a vast leap in human processing power.

Overview
Encoded Engrams are sold by the Cryptarch, and are coded with the patterns of known items, such as a particular section of armor or class of weaponry. Once purchased by the player, the engram is converted into a random example of that item by the Cryptarch. While decoding an engram will generate a random item, it's still possible to know the type of item that will be discovered. Each Engram will indicate whether the item is armor, a primary weapon, a special weapon, a heavy weapon, or an item shaped like the Engram. The quality of the item is also identified, as Engrams use the same color coding as weapons and armor: White for Basic, green for Uncommon, blue for Rare, purple for Legendary, gold for Exotic.

Encrypted engrams are defined in-game as having "unusual properties". These must also be taken to the Tower where the Cryptarch will convert them if (in certain cases) only after he has attained the necessary Rank. The Cryptarch is also known to have these rarer Engrams for sale from time to time, which are more common if his skill is higher.

Engrams are also found as loot, and appear as colored crystals on the ground (white for Encoded, green for Encrypted, blue for Decoherent, purple for Legendary, yellow for Exotic). Enemies may drop them randomly, or they may be picked up from boss encounters or inside chests. Any engrams that the player hasn't picked up may show up in the Postmaster's office.

Finally, there are also occasions where Guardians may encounter Engram-like objects; Araskes, the Trickster notably disguised explosives as Exotic Engrams, and the Grasp of Avarice is filled with both unstable Exotic Engrams and what appear to be "discharged" or "inert" crystals that resemble Engrams in shape but have a dull purple-ish coloration.

Decoding Engrams
Engrams have a chance of being decoded into an item that is higher or the same quality as the Engram itself. That item will almost always correspond to the type of Engram it comes from; the exception to this is that sometimes a Rare Engram will decode into a Mote of Light or Strange Coin instead. Also, certain items will never be decoded from an engram and can only be acquired a certain way; this applies to any item acquired through a Raid, Exotic Bounty, the Iron Banner, Trials of Osiris, or as a reward for a Story mission.

There are nine Weapon Engrams, seven Armor Engrams, and three Class Engrams. Each is marked with a weapon or armor piece symbol to indicate what type of gear it is (Shotgun, Auto Rifle, Machine Gun, etcetera).

Umbral Engrams
Introduced during Season of Arrivals and returning in Season of the Chosen and every subsequent season for Destiny 2, Umbral Engrams are a less common variant of Legendary Engram which can be "focused" into dropping more specific kinds of loot, such as one of two short range weapons, seasonal armor with a specific high stat, and so on; this typically requires additional investment of seasonal resources and/or appropriate Triumph unlocks, which can also grant additional benefits such as a chance for decrypted weapons to have an additional selectable perk in their third and/or fourth columns.

Focusing occurs at the H.E.L.M., whilst unfocused Umbral Engrams can be decrypted as-is at Master Rahool in the Tower if no specific reward is desired.

List of appearances

 * Destiny
 * Destiny 2