How does a computer virus getting formed?

How a computer virus forming? I have many recent viruses, but thanks to Norton Anti-Virus and Anti-Malware Malwarebytes my computer 100% secure. But how can a computer virus created? Do people really do, and they spread on the Internet? Please tell me more about computer viruses, Because I’m not too this I just got rid of them.

Related posts:

  1. Computer Care, Can I Do It Myself?
  2. What computer company has good quality for gaming?
  3. Computer question (How long does an average person keep a computer for?
  4. Hot Download: Sunbelt Vpire
  5. Can connecting another computer to my network influence the connections of the other computers?