An itinerary is your travel plan — where you will go and when you will be there.
If you make plans to fly to Paris from Beijing or take a train to Chicago from Mexico City, you will need an itinerary. That means you will have a plan that displays how you will get from point to point in your travels and when you will be at each point. This word comes from the Middle English itinerarius and is defined as being "about a journey." Itineraries can be really useful because if you give your mother yours, she will always know where you are!