The document discusses context diagrams and data flow diagrams (DFDs). It provides examples of a context diagram for searching an online database and using an ATM. It also gives steps for creating a DFD, including deciding on processes, entities, data flows, and storage. An example DFD is provided for borrowing a book from a library. Finally, the document describes a proposed self-checkout system for a video store and asks to draw the DFD showing the three processes of membership validation, borrowing limit check, and payment processing.