Mount Zion, the Mountain of Zion, or simply Zion (also called Sion) was a mountain located within the land of Canaan, which is most notable for being the land that the city of Jerusalem was built on. Zion was the original and subsequently the symbolic name of the mountain that David made in the city of Jerusalem when he took it from the Jebusites. It was called "the city of David" and was often used as a synonym for the whole city of Jerusalem, despite it referring to the mountain the city was placed on itself.
Mount Zion centrally located in Jerusalem, Israel, became a symbol of the functions of the city as capital and site of Temple there, despite the Temple being located on the neighboring Mount Moriah. References to the temple and to "Mount Zion" are to the presence of the Lord in the midst of his people, sometimes referred to as the "daughters of Zion."
In one place the spelling of Mount Sion refers to Mount Hermon rather than to Jerusalem. All references to "Mount Sion" in the New Testament are referring to mountain of Zion. Zion its often used as symbolism of the metaphorical aspect of Jerusalem being compared to Heaven and is used to refer to the people of Israel in its entirety as God's chosen. Evenmore this is often used as symbolism when discussing the rulership and reign of Jesus Christ