Hub and Router
A network hub or repeated hub is a device for connecting multiple twisted pair or fiber optic Ethernet devices together and thus making them act as a single network segment. Hubs work at the physical layer (layer 1) of the OSI model. The device is thus a form of multiport repeater. Repeater hubs also participate in collision detection, forwarding a jam signal to all ports if it detects a collision.
A router is an electronic device used to connect two or more computers or other electronic devices to each other, and usually to the Internet, by wire or radio signals. This allows several computers to communicate with each other and to the Internet at the same time. If wires are used, each computer is connected by its own wire to the router.
Keyboard and Mouse
In computing, a keyboard is an input device, partially modeled after the typewriter keyboard, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches. In computing, a mouse (plural mouses, mice, or mouse devices.) is a pointing device that functions by detecting two-dimensional motion relative to its supporting surface.
A computer fan is any fan inside a computer case used for cooling purposes, and may refer to fans that draw cooler air into the case from the outside, expel warm air from inside, or move air across a heatsink to cool a particular component. The use of fans to cool a computer is an example of active cooling.