Computerknowledge in its memory and does calculations on that knowledge. This knowledge is stored in symbols; it is called data. A computer usually has a monitor to show results. However, some computers can speak; computers which can speak can be used for voice mail.
A computer frequently requires a boot device. The boot device contains the computer's operating system and data. Some people also think that computers are less useful if they do not have access to the Internet. They think this because the Internet allows the computers to send and recieve data across the world.
A computer is now almost always an electronic device. It usually contains materials which are toxic; these materials will become toxic waste when disposed of. When a new computer is purchased in some places, laws require that the cost of its waste management must also be paid for. This is called product stewardship.
Computers become obsolete quickly. Very often they are given away and new ones replace them within two or three years. This makes the problem worse. Computer recycling is thus common. Many projects try to send working computers to developing nations so they will not become waste as quickly.