Some good things are meant to be only temporary, such as the display of a calculator or
an online chat window. However, most programs can save their documents to a file and
open and load that file to re-create a document that has been stored. MFC simplifies
this by using archives and extending the use of the stream I/O operators >> and <<. You
learn all about reading and writing to files in Chapter 7, "Persistence and File I/O."