Deku Scrubs are a race of creatures from The Zelda series. They are plant-like creatures, with bulbous heads & bodies, with small plantlings growing out of different parts of their body. They also have a large snout-like mouth, which shoots nuts at any nearby enemies, much like Octoroks.
The Deku in The Legend of Zelda: Ocarina of Time are basically normal, mischievous (but not evil) enemies. They are easily defeated by deflecting their Deku Nut attacks with a shield, back into their faces. Some Business Scrubs will even sell Link items inside of dungeons. Link first runs into one inside the Great Deku Tree. The relation between Deku Scrubs and the Great Deku Tree is unclear, especially in Majora's Mask, where Deku Scrubs are portrayed as another race of Termina instead of normal creatures.
In Majora's Mask, there is no mention of the Deku Tree. The Deku Scrubs of Termina are much more intelligent and civilized, living under the rule of a monarchy. Here, scrubs are not only able to shoot nuts at enemies, but also use magic to glide with leaves above their head. They are also rivals with the local Monkeys.
Many tools used by Link seen in the Zelda games can be seen as Deku Technology. Below is a list of them.