star network
Network in which all devices are connected to a central unit (here, a hub) in the shape of a star.
desktop computer 
Small workstation or microcomputer designed for stationary use.
hub 
Unit that receives all messages sent by the devices connected to it and redistributes them to all users.
server 
Computer that hosts various resources (including files, applications and databases) and places them at the disposal of all the devices connected to the network.