How to Read a tree diagram when studying probability

In this video the tutor shows how to read a tree diagram. He shows an example of a tree diagram and says that tree diagram represents the choices made by a student in a cafeteria by ordering different kinds of foods and the chain in which the they are ordered. Now every combination that a student can choose at their lunch is mapped out in the form of a tree diagram. Now any choice a real student takes at the cafeteria can be mapped out to the tree diagram through the different branches. Now the tutor shows how to further read the tree diagram and make useful calculations from it. This video shows what a tree diagram is and how to read it.