A scenario involving a series of steps taken by a user while they are interacting with a system.
A user journey is a series of steps (typically 4-12) which represent a scenario in which a user might interact with the thing you are designing. They can be used for 2 main things:
- Demonstrating the way users currently interact with the service /
website / product - Demonstrating the way users could interact with the service / website / product
Reference: http://theuxreview.co.uk/user-journeys-beginners-guide/