Why does a salt shaker balance on a table when you place it on its edge?

A salt shaker balances on its edge due to the principles of stability and center of mass. When placed on its edge, the center of mass is directly above the base of support, which is narrowed to the line along the edge. This configuration allows for a stable equilibrium as long as the center of mass remains over the base; however, any slight disturbance can shift the center of mass outside the base, leading to tipping.