Social mobility refers to movement between social classes or statuses. There are five types of mobility: territorial mobility involving relocation; vertical mobility involving upward or downward movement in rank; horizontal mobility involving a change in profession without rank change; inter-generational mobility between generations; and intra-generational mobility involving status changes within a generation. Causes of social mobility include dissatisfaction with one's current condition, adoption of new conditions, industrialization, education, urbanization, and improved transportation and communication.