Developed by Qahnaarin of a much older time these were how ships traveled back int he ancient times. It was essentially a contained wormhole that could be sent to another stargate to cut travel time. The Qahnaarin and the Channan were the only 2 races to use such technology. However after much struggle, alot of these gates were torn down by future races after it was discovered they could be weaponized. That coupled with the fact that FTL systems were now common on starships, making Stargates irrelevant unless traveling massive distanced between galaxies.