How does a virus infect a computer?

Different viruses have different ways of infecting a computer or floppy disk. Infection can occur if you start your computer from an already infected disk, use an infected file or application on your computer, or use your disk in an infected computer that then spreads the infection to your disk.  To help keep Windows machines more secure, install the latest security patches and software updates.  Also, have secure passwords to log onto your computer with and keep your anti-virus protection up-to-date.