This chapter introduced two new concepts: property paths and shapes. They arose as a result of the hybrid nature of items and folders exposed through Exchange Web Services. Really, these concepts aren’t that new but are simply concepts brought over from the relational database world. Property paths represent a way to refer to a property as a piece of metadata, independent of the objects that hold the values for that property. If you say, "Give me the list of people that this message was sent to," the "list of people" is a property path that turns into a value when the request is fulfilled. This chapter also touched on response shapes and how they affect the data that is returned for both items and folders.