The document discusses how to install SSH in an Ubuntu server. SSH (Secure Shell) provides encrypted data transfer between a client and server. There are three initial packages needed for SSH in Ubuntu: openssh-server contains the SSH server, openssh-client contains SSH clients, and a metapackage for both. The document then outlines the steps to install SSH using apt, including verifying the installation, checking that the SSH daemon is running, and testing SSH access from a client.