Why were computer viruses invented?

talking about the reasons why programmers create viruses, worms and the likes… Reasons varies actually from one programmer to another.

1. They write this kind of codes as part of their research.
2. These are just pranks, vandalism etc
3. A way of spreading Words ie announcement, greetings, political message etc
4. They use them for extortion, theft etc
5. A way of testing a product, application or any software.
6. The way to attack one's application, works, job, etc.

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