This chapter is concerned with the various facilities provided for communication between Magma and its environment. The first section describes character strings and their operations. Following this, the various forms of the print-statement are presented. Next the IO type is introduced and its subtypes described, followed by a summary of the allowed I/O operations on these types. The chapter concludes with a section listing system calls. These include facilities that allow the user to execute an operating system command from within Magma or to run an external process.