It is the first time that Adobe has allowed dynamic adverts into its PDF (Portable Document Format) files.
Dynamic adverts can be changed for particular audiences or rotated to make sure that a particular user never sees the same advertisement twice.
PDF files can be created by a range of software and can then be read by people who have a PDF reader, such as Adobe's Reader.
The PDF format has proved popular with both companies and home users, and has been used to produce large reports and shorter newsletters, as well as preparing documents for printers.
