anti virus has no disadvantage other then occasionally wanting you to restart your computer for a update.advantages keeps you safe think of it like thisyour firewall is the condom.your anti virus is...
Good anti virus software costs a lot of money, plus the yearly (and sometimes monthly) fee, and some anti virus software updates every day, which can slow down your internet connection when you start...
The virus could delete files and find out your email passwords, account passwords, credit card number, etc. and it will make your life really difficult.
Advantages it makes operating system developers make their system more secure. Disadvantages it damages files and causes security problems in companies