The Macro virus is the most common type of computer virus. The ILOVEYOU virus is one example of this type of virus which hides in a document or spreadsheet.
downloads or e-mails
Viruses can steal information or destroy computers. The most common virus only steals improtant information. The worst type of virus can destroy a computer, and that computer can never be used again.
the computer doesn't work
It depends on the type of virus. The most common is the Trojan virus, which will hide inside an "ordinary file" and start spreading to other files through registry keys and documents/software installed. At least that is the most common.
Almost any activity on the Internet can cause your computer to be infected by a virus. The most common are emails, social media (such as forums, Facebook, etc), pictures, and downloads.
through e-mail amd opening files on it
getting a virus on your computer
in the post :D