Questions regarding the use of "anti-virus" or similarly categorized
"Internet security" products frequently arise on this site. Many of them
are from new Mac users whose previous computer experience was limited to
traditionally virus-prone Windows PCs. Early Microsoft Windows versions
were notoriously vulnerable to unauthorized modifications and malicious
interference, which gave rise to a cottage industry of "anti-virus"
software companies responding to a need for the operating system
security Microsoft neglected to provide.
Apple and Microsoft's respective operating systems were originally
conceived and developed completely separately, for use with completely
different hardware, and their evolution has only diverged since their
inception. In recent years Microsoft has made great strides in
protecting its Windows operating system, but owing to macOS's original
concept as a multi-user, multitasking operating system incorporating a
fundamental requirement to keep users separate from one another, it was
never as vulnerable to begin with. With each new release, macOS has only
grown more secure from unauthorized tampering.
It's important to understand the nature of threats that exist today, and
to appreciate the fact that "anti-virus" software peddlers have been
reduced to abject panic as their traditional Windows PC market suffers
its inevitable decline. The cottage industry described in the first
paragraph has since grown to a multi-billion dollar behemoth with
entrenched interests—an enormous beast that demands to be fed. The PC
market's demise has led to a predictable response from them and shills
who represent their interests, asserting that since Macs are rapidly
growing in popularity, they have become just as vulnerable to "viruses"
as PCs, implying an even greater need for the products they sell. It
just isn't so.
What is true is that the growing base of Mac users are being
increasingly targeted and exploited for scams that seek to defraud them
of their hard-earned money. Criminals who seek to do that cannot succeed
without your help. Don't give them the satisfaction.
The following describes simple principles that will serve to protect
your Mac, and yourself, from the various threats that exist today. It's
long, but if you read nothing else, read the first three numbered points
and the Summary at the end. They are equally applicable to Macs, PCs,
mobile devices or anything else that uses software to communicate with
the world beyond it.
There will always be threats to your information security associated
with using any Internet-connected communications tool:
You can mitigate those threats by following commonsense practices
Delegating that responsibility to software is an ineffective defense
Assuming that any product will protect you from those threats is a
hazardous attitude that is likely to result in neglecting point #1 above.
macOS already includes everything it needs to protect itself from
viruses and malware. Keep it that way with software updates from Apple.
Rather than asking which non-Apple "anti-virus" or "Internet security"
product is best, a much better question is "how should I protect my Mac".
This is an extract from https://discussions.apple.com/docs/DOC-8841
Do, please, read the rest of the advice provided at the link.