Basic elements of a computer system are Mouse, Keyboard, monitor, memory, CPU, motherboard, Hard Disk, Speakers, Modem, power Supply, and processor.
Mouse: Mouse is sued for operating the system. You can also use computer without mouse, as by using motherboard but in this case it will be very tough to use a computer. These days optical mouse is used because it is very efficient to use as compared to simple mouse.
Keyboard: Keyboard is used to giving input to the system and system gives output to the user. There are many things which we cannot do without keyboard as we cannot write any thing without a keyboard.
Monitor: Monitor is very essential part of a computer system. It is used to display things which we perform on a computer.
Motherboard: Motherboard is also a necessary element of a computer system. It contains different elements as memory, processor, modem, slots for graphic card and LAN card. Memory is sued to run programs on a computer. LAN card is sued for making a network between computers.Hard Disk: Hard disk is used to store data permanently on computer.
Modem: Modem is used to connecting internet. Two types of modems exist. One is known as software modems and other is known as hardware modems.
Speakers: Speakers are also included in basis elements of a computer. But it is not necessary as a computer can perform its function without this. However, we use it to for multiple purposes.