What does a computer virus do to your computer?

Answer 1

It can do a multitude of things, all harmful. Many viruses, which disguise themselves as tracking cookies, are meant to allow access to personal information that you give out over the internet. If you are shopping and this happens, it can be used for identity theft. Viruses can also slow down your computer significantly, erase information, destroy vital data, even shut down your computer, but those are rather extreme ones and pretty rare.some viruses encrypt themselves in a different every every time so it is impossible to find them using anti-virus as anti-virus uses a signature string to locate them.

A virus can destroy your computer and it can delete all of your personal data and even shut down all the computers with internet connection in your house, even when you are watching television.

Answer 2

Depends on the Type.

Create Registry Values

Edit Registry Values

Create Files

Duplicate Itself and Install to other Folders..

Some Allow the hacker to control your computer remotely using a Remote Connection. They can do everything you can do including steal passwords, download files to your computer, delete files, open web pages, anything.

Some just cause damage and delete files your computer needs to work

Some are just annoying and slow the computer down

Some display advertisments for things such as rogue Scanners