MacKeeper Is Malware
hypertexthero.com
hypertexthero.com
Additionally, the information on AV and how it works is sloppy. This is already covered well by other comments here, so I won't belabor it.
I don't care about any such fine distinction. It's an annoying crapware that pops out of adds that pretend it's a system message for my Mac and that I'll be in trouble if I don't use it.
That's malware enough for me.
Strictly speaking, this isn't true. The major AV companies use file behaviours to try to stop viruses as a first line of defense, something like "if a file is an executable and it tries to run some manner of encryption on files in the My Documents folder, its likelihood of being a virus is high". AV companies use file checksums as a last-ditch effort because most viruses out there are polymorphic (they have some unused data section at the end that randomly changes, which busts checksum detection).
A lot of AV companies also offer virus cleanup services, so if you do happen to get hit by a virus that snuck by, they can help reduce the damage.
Nobody's saying "use AV and you don't have to ever worry again". AV is just another piece of the defense puzzle, along with user vigilance (don't click that link in that email from "eBay"), operating system restrictions, network restrictions (to help prevent data egress), and so on.
This is simply not true. Here's an test where AV products are frozen before the brand new malware samples are collected: http://www.av-comparatives.org/retrospective-test/
You don't need an antivirus because virus definitions are slow to update? Fine, but what about old virus? Am I protected by magic?
Also, I feel like the increase in OSX popularity will result in an increase in malware for it, so I'm not sure for how long "OSX is virus-free" will be valid