Most always a solid.
Salt is an ionic compound. The interlocking bonds between the positive sodium ion and the six surrounding chloride ions ( and visa versa) create a high melting point for this solid.
While salt can exist as a liquid in a pure form it is more common to find salt as brine. Brine is a solution of salt and water that is highly concentrated. There is a enough water to separate the positive and negative ions but not completely so the brine remains in liquid form.
Salt never exists as a gas. The ions of Chlorine would form back together as
So while salt can be liquid under high temperature and pressure, it is almost always a solid and never a gas.