The Host refers to a remote module installed on a target, or remote, PC. This module facilitates both unattended and attended access.
The Viewer is a "command center" utilized by support technicians and administrators. It serves as a central hub for various tasks, including managing the address book, initiating remote sessions, and overseeing license management.
If Host and Viewer share the same LAN and subnet, you can use the Host IP address or computer name for connection. See Connecting over LAN.