Viruses
Viruses are written by malicious programmers who wish to cause problems for other computer users.
The primary source of infection these days are emailElectronic mail. A method for sending messages and files to other people.attachmentA file that is sent with an email. followed by illegal softwareThe programs, applications and data in a computer system. Any parts of a computer system that aren't physical. and infected files from the internetA global network connecting millions of computers.. If you have up to date anti-virusAnti-virus software scans all forms of storage devices for viruses (programs harmful to computers) and, if found, attempts to remove them. software installed this will immediately warn you of any infection. If not, there is usually no evidence of the virus and the user is not usually aware of it until something goes wrong.