What is the best antivirus for Mavericks? (Either paid or free)


What is the best antivirus for Mavericks? (Either paid or free)
I currently have Avast installed on my Mac, but what wondering if there is a better alternative out there for Mavericks? This is my work computer, so I heavily use it which is why I really want to make sure that nothing happens to it.
Anti-virus software serves no beneficial purpose on a Mac. Remove the Avast garbage by using its uninstaller, which will effectively remove it as well as the objectionable adware it installs. Never install it, or anything like it, ever again. Not all such trash is as easily removed.
... I really want to make sure that nothing happens to it.
Something will happen to it, eventually, but any concerns regarding "viruses" on a Mac should be dead last.
Implement a reliable backup strategy, so in the event your Mac breaks or becomes lost, recovery will be a non-event. Time Machine is included on all Macs. All you have to do is use it. To to that read Mac Basics: Time Machine backs up your Mac.
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.
OS X already includes everything it needs to protect itself from viruses and malware. Keep it that way with software updates from Apple.
A much better question is "how should I protect my Mac":
Never install any product that claims to "clean up", "speed up",  "optimize", "boost" or "accelerate" your Mac; to "wash" it, "tune" it, or to make it "shiny". Those claims are absurd.Such products are very aggressively marketed. They are all scams.
Never install pirated or "cracked" software, software obtained from dubious websites, or other questionable sources.
Illegally obtained software is almost certain to contain malware.
"Questionable sources" include but are not limited to spontaneously appearing web pages or popups, download hosting sites such as C net dot com, Softonic dot com, Soft pedia dot com, Download dot com, Mac Update dot com, or any other site whose revenue is primarily derived from junk product advertisements.
Don’t supply your password in response to a popup window requesting it, unless you know what it is and the reason your credentials are required.
Don’t open email attachments from email addresses that you do not recognize, or click links contained in an email:
Most of these are scams that direct you to fraudulent sites that attempt to convince you to disclose personal information.
Such "phishing" attempts are the 21st century equivalent of a social exploit that has existed since the dawn of civilization. Don’t fall for it.
Apple will never ask you to reveal personal information in an email. If you receive an unexpected email from Apple saying your account will be closed unless you take immediate action, just ignore it. If your iTunes or App Store account becomes disabled for valid reasons, you will know when you try to buy something or log in to this support site, and are unable to.
Don’t install browser extensions unless you understand their purpose. Go to the Safari menu > Preferences > Extensions. If you see any extensions that you do not recognize or understand, simply click the Uninstall button and they will be gone.
Don’t install Java unless you are certain that you need it:
Java, a non-Apple product, is a potential vector for malware. If you are required to use Java, be mindful of that possibility.
Java can be disabled in System Preferences.
Despite its name JavaScript is unrelated to Java. No malware can infect your Mac through JavaScript. It’s OK to leave it enabled.
Block browser popups: Safari menu > Preferences > Security > and check "Block popup windows":
Popup windows are useful and required for some websites, but popups have devolved to become a common means to deliver targeted advertising that you probably do not want.
Popups themselves cannot infect your Mac, but many contain resource-hungry code that will slow down Internet browsing.
If you ever see a popup indicating it detected registry errors, that your Mac is infected with some ick, or that you won some prize, it is 100% fraudulent. Ignore it.
Ignore hyperventilating popular media outlets that thrive by promoting fear and discord with entertainment products arrogantly presented as "news". Learn what real threats actually exist and how to arm yourself against them:
The most serious threat to your data security is phishing. To date, most of these attempts have been pathetic and are easily recognized, but that is likely to change in the future as criminals become more clever.
OS X viruses do not exist, but intentionally malicious or poorly written code, created by either nefarious or inept individuals, is nothing new.
Never install something without first knowing what it is, what it does, how it works, and how to get rid of it when you don’t want it any more.
If you elect to use "anti-virus" software, familiarize yourself with its limitations and potential to cause adverse effects, and apply the principle immediately preceding this one.
Most such utilities will only slow down and destabilize your Mac while they look for viruses that do not exist, conveying no benefit whatsoever - other than to make you "feel good" about security, when you should actually be exercising sound judgment, derived from accurate knowledge, based on verifiable facts.
Do install updates from Apple as they become available. No one knows more about Macs and how to protect them than the company that builds them.
Summary: Use common sense and caution when you use your Mac, just like you would in any social context. There is no product, utility, or magic talisman that can protect you from all the evils of manki
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