To get any real benefit from the guide, the reader must have access (whether by a machine in front of them or via an SSH connection)[2] to a computer running Linux. Similarly, for the reader to benefit from sections in the guide that cover specific programs (such as Section 5.2, “GNU Emacs”), the software under discussion must be installed.
[2] Wikipedia's article on SSH (also called Secure Shell) describes it as “a network protocol that allows data to be exchanged using a secure channel between two networked devices.” Secure connections made by SSH form the basis for the secure file transfer protocols SFTP and SCP, both of which are are discussed in Chapter 4, Secure file transfer.