A user journey represents a sequence of events or experiences a user might encounter while using a product or service. A user journey can be mapped or designed to show the steps and choices presented as interactions, and the resulting actions.
A user journey can be mapped in order to better understand the flow and make improvements, or it can be designed from scratch based on a desired specification or story.
When designing an experience it is usually only necessary to document a user journey is it is of a certain complexity. For many websites and applications it is possible to agree on user journey based on a specification, sitemap or wireframe. If there are many choices, states or possible scenarios leading to bifurcated experiences, documented mapping of the user journeys will help a project team to better understand the complexity of the tasks at hand.
The user journey is the responsibility of everyone on the design who can affect the user experience.
User journey mapping
The UX Review