transition

the act of passing from one state or place to the next

an event that results in a transformation

a change from one place or state or subject or stage to another

a musical passage moving from one key to another

a passage that connects a topic to one that follows

cause to convert or undergo a transition; "the company had to transition the old practices to modern technology"

make or undergo a transition (from one state or system to another); "The airline transitioned to more fuel-efficient jets"; "The adagio transitioned into an allegro"