How do Viruses Spread?

Viruses spread when you run an infected program or start up your computer from a disk that has infected system files. Once a virus is in memory, it usually infects any program you run. If your program is a network application you can infect others on the network who use the application.

While many viruses stay active in memory until you turn off your computer, others stay active only as long as the infected program is running. Even though turning off your computer or exiting the application removes the virus from memory, the virus will still reside on the infected file, disk or application and will activate the next time you start your computer or run the application.

Can you get a virus from infected data?

Since data is not executed, your computer cannot become infected from data. Accordingly, email per se cannot transmit viruses and reading an email message will not infect your computer. However, attachments to email messages mail contain .exe files which when opened can infect your computer.

Can your computer get infected by being connected to a network?

You can not get infected by being connected to a network such as the internet, a bulletin board system (BBS), or even a local area network. You can of course download a program from the internet that contains a virus that only infects your computer if you execute the program.

Can you get a virus downloading a program?

Downloading a program in itself will not infect your computer. As indicated, if you download a program that contains a virus, you can get infected if you run the program.