Tasers, (named for "Thomas A. Swift's electric rifle" their creator) also known as stun guns, are non-lethal weapons built and used by the Tau'ri.
Although their uses are similar to those of Zat'nik'tels and Wraith stunners, their workings are much different. They work by firing a pair of cables into the victim, through which an electric current is passed, paralyzing the target and causing him/her to fall to the ground. As well as having a very limited range, due to it using the cables to transfer the current, it also has the weakness that its effects last only as long as the cables remain in place and connected to the device. This is in contrast to the two weapons mentioned above, which force a long-lasting period of unconsciousness after hitting a victim.
Tasers were used by the Atlantis expedition during their first year of operation to capture a Wraith for information. It was shown that tasers have the ability to bring down a Wraith, but they would retain sufficient motor control to initiate a self-destruct. (SGA: "Suspicion")
One year later, after Colonel Steven Caldwell was revealed to have been taken as a host by a Goa'uld agent of the Trust, Lt. Colonel John Sheppard used a taser on him after the Goa'uld was subdued by Ronon Dex. The electric shock allowed Caldwell to regain control from his symbiote briefly and give them the code they needed to restore the ZPM failsafes. The taser only appeared to stun the Goa'uld briefly as Caldwell was visibly fighting to maintain control moments later. (SGA: "Critical Mass")