Recently, Apple released the newest version of their operating system (OS), OS X 10.9 Mavericks, for free to all users that were at least on OS X 10.6 (and had compatible hardware). This was a pretty bold move on Apple's part to just stop charging for the Operating System itself, and was welcomed by users across the tech spectrum, especially since most key Apple software was now also being released for free.
Months later, it seems that Apple really really really wants everyone to be using Mavericks, and they're doing so by putting all their focus on Mavericks at the expense of their older versions of the OS. According to Apple's security release schedule (apple.com), there has been a lack of security updates directed at the older OSes. Mavericks itself came with a bundle of security patches for some of the core parts of OS X, such as some minor unix utilities which needed bug fixes and some Apple software that wasn't working quite as expected.
Security patches and bug fixes are normal for operating systems, and it's not uncommon for all OSes to have a slew of security patches out each month. Apple typically prefers to release them in larger bundles as opposed to individualized fixes, though in the past they have released "hot fixes" to address major issues. But for Apple to be turning away from their previous OSes so quickly, it seems like a real push to get users onto Mavericks as soon as possible and keep them there.
So is your Mac less secure if it doesn't have Mavericks? Absolutely. Many of the patches are for some fairly critical vulnerabilities, and while the virus and malware scene for Mac still hasn't taken off in over a decade, that doesn't mean they don't exist. The best security practice you can have for your Mac right now would be to keep it up to date with software updates from Apple, including Mavericks.
Mavericks is free! The upgrade is very simple, requiring a bit of time to download the software. If your computer is Mavericks compatible (wikipedia.org), you most definitely should upgrade. We strongly recommend backing up all your important documents before trying to perform the upgrade. If you need assistance with upgrading your Mac, or have questions, please stop in or contact the Help Desk, and we'll be more than glad to assist! Contact information at the end of this post.
A final note on OS X Security -- while OS X is not free of vulnerabilities, there still is not a strong case for using an anti-virus on your Mac at this time. Most of the anti-virus systems currently available are just sub-par, often eating up a lot of the Mac's power looking for viruses and malware that just likely aren't going to hit your machine. Apple has and keeps its own anti-malware service running in the background on your Mac; it isn't something you can interact with, but it is updated and worked on by Apple.
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