Think about the last time you have made a purchase. Now consider all the steps - online and offline - that brought you from need to conversion (and over). That is your customer journey, a map that you can break up into many different pieces.
Customer experience looks like a puzzle, that you - as a business - can shape and analyze using a specific tool: the customer journey map. As the years pass by, new technologies change the perspective, and so the map needs to become more structured, to include the new touch points.