What is the Kingdom of GOD?

JESUS said in Mark 1:15, "The kingdom of GOD is at hand; repent and believe in the gospel." The kingdom of GOD is where GOD is king, HE rules and reigns in HIS people and through HIS people. HE calls us to listen to HIM, trust HIM and follow HIM as King. "Seek first the Kingdom of GOD"...JESUS said.