If this book were about PC maintenance, one of the first steps would have been to install antivirus software. For Windows users, malicious software (or malware) has become epidemic in recent years, leading to untold grief and loss of time, money, and data. Among the varieties of malware are viruses (and their close cousins worms and Trojan horses), spyware (programs that spy on your computer usage, collecting sensitive personal data), and pop-up ad programs. Luckily, very little malware runs on Mac OS X: as of the time I wrote this, I could count on one hand the programs of this sort that have been found "in the wild."
Even though Mac users have been fortunate so far, we would be wrong to assume our computers are immune to infection. Sooner or later, someone is bound to come up with malicious software that does serious damage to Macs, and when that happens, those with enough foresight to have installed antivirus software will be much more likely to continue merrily with their work while the rest of us struggle to restore our systems.
Furthermore, many kinds of malware spread via email, so you could unwittingly serve as a carrier by forwarding messages containing viruses to your Windows-using friends.
Your best defense is to load antivirus softwareand keep it up to date. Developers release regular updates (to handle the latest threats), and you must be certain to configure your preferences to download them automatically as soon as they appear.
Although having antivirus software is better than not having it, and having up-to-date antivirus software is better still, there are no ironclad guarantees. A particularly wily virus might still sneak by. So you should still exercise caution, and especially avoid opening iChat or email attachments from unknown sources.
Antivirus software available for Mac OS X includes the following: