Copies itself and be able to send itself to other computers freely. Based on email, or operating system vulnerabilities, often not widely believed to infected files. What it did do is often damaging to the traditional system.
Can copy itself and send itself to another computer. Users want more freely. By email or vulnerabilities of the operating system. Usually does not spread to the file. What it's doing is often damage to the network.
Copy itself, and can submit themselves to the computer machine model. Other freely. By using e-mail or operating system vulnerabilities. Usually does not infect other files to fire What it does is often damaging to the beverage system