A Federation farming world where Sergey and Helena Rozhenko brought up the orphaned Worf after the Khitomer massacre, before the family moved to Earth.
Gault is a Federation farm colony mentioned in the Next Generation episode Heart of Glory.
Speaking to the renegade Klingons Korris and Konmel, Worf explains how he came to serve in Starfleet. After the Romulan attack on Khitomer he was found in the rubble by a human Starfleet officer, who took the boy home to Gault and raised him with his wife as their own son.
Worf spent his early childhood there before the family moved to Earth. His account of growing up as the only Klingon among humans, struggling to control his instincts, is what leads Korris to believe Worf might join them.