There is described a method of communicating over a public data network, for example the Internet. A user of a public PC, for example one located in an Internet café, uses the Internet browser provided on the public PC to downloaded from a remote trusted web site a secure Internet browser that then runs within the browser provided on the public PC. The user uses the secure Internet browser to browse the Internet. The secure browser has been configured so that no copy of information transmitted into the network or downloaded from the network is cached or otherwise recorded on the hard disc of the terminal. The user may thus browse the Internet without leaving a record of sensitive information (e.g. credit card details) used in the browsing session at the public terminal.