The phrase "to cross over" means to move from one place, state or condition to another. It can refer to physically crossing a boundary such as a river, bridge or border, but it also has metaphorical meanings in various contexts. For example, in music, "crossing over" refers to an artist's success in reaching audiences beyond their original fan base and gaining popularity with mainstream listeners. In sports, the term can refer to a player transferring from one team to another or even changing positions within the same team. Figuratively speaking, it could also mean transitioning from one phase of life to another, such as moving from adolescence to adulthood or leaving an old job for a new career opportunity.