Every system may be a desktop or laptop has hardware and software has two types of components. That is hardware components and software components. Both are equally essential for the performance of the system. The hardware components are again divided into some major groups. Each group again has several hardware components. The main parts of a computer are CPU (Central Processing Unit), Monitor, Keyboard and Mouse (optional). CPU is also called the brain of the computer. All the matter is saved in CPU.The memory is again divided into two divisions. One is RAM the other is ROM. The speed of a system mainly depends on the capacity of both RAM and ROM.Monitor is used to display. It is also called as output device. Keyboard and mouse are used to give inputs and so called input devices. When we come to the software there is some software that is essential for running the system such as operating system. Apart from this there are many softwares which are required by the organization to improve their performance quality and quantity. Now let us consider users. Every user using the system saves and shares the information. Information stored in CPU. There are various ways to share the information. Internet is one of the options in which data can be shared easily from any part of the world to any part of the world. The other one is Local Area Network where we can share the information only with the computers on our network. There are many such sharing options available. You can access one system with the help of other. The other main threat faced is virus. Though there are antivirus softwares there are some virus which lets the creator use the information of the system the virus attacks.