Answer:

1. system unit is the part of A computer that houses the primary devices that perform operations and produce results for complex calculations.
2. expansion bus is an assortment of wires that allows for computer expansion with the use of an expansion board, a printed circuit board inserted into an expansion slot on the motherboard or backplane that provides additional features to a computer system.
3. power supply unit (PSU) converts mains AC to low-voltage regulated DC power for the internal components of a computer.
4. hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage and one or more rigid rapidly rotating platters coated with magnetic material.
5. A DVD is a type of optical media used for storing digital data. It is the same size as a CD but has a larger storage capacity. Some DVDs are formatted specifically for video playback, while others may contain different types of data, such as software programs and computer files.
6. NIC provides a computer with a dedicated, full-time connection to a network. 
7. network device is a node in the wireless mesh network. It can transmit and receive wireless HART data and perform the basic functions necessary to support network formation and maintenance. Network devices include field devices, router devices, gateway devices, and mesh hand-held devices.
8. Network functions virtualization is a network architecture concept that uses the technologies of IT virtualization to virtualize entire classes of network node functions into building blocks that may connect, or chain together, to create communication services.
9. WANs can facilitate communication, the sharing of information and much more between devices from around the world through a WAN provider.
10. local area network is a computer network that interconnects computers within a limited area such as a residence, school, laboratory, university campus or office building.