does my macbook air have a built in virus scan? how can I access and use it? also any recommendations of what software if this is not avail ?

No, you don't need specific anti-virus software like on Windows and Android. OS X has built-in protections against malware such as those described here: OS X Yosemite: Protect your Mac from malware and here: OS X: About Gatekeeper - Apple Support

No, OS X does not come with any built in virus protection however most OS X users do not use one including myself.

While OS X is, of course, vulnerable to viruses the general feeling is that it is not needed because:

1. The underlying UNIX operating system is considered to be inherently more secure [than Windows]
2. As it has a vastly larger market share Windows receives most of the attention from malware authors

For those same reasons this applies to Linux distributions as well. I have been running my Mac for over two years and have not had any apparent problems with viruses or other malware.

If you still feel you want virus protection there are third party anti-virus software packages available for OS X but I have no experience with any of them so cannot make a recommendation. I do know that Norton and Mcafee are both available for OS X.

The feature that David referred to does not have any kind of scanner. It basically prevents (or warns - depending on your settings) unknown software from running on your system. Note that even if software is unknown to Apple it is not necessarily malware. The vast majority of unknown software is fine (most of the software I use is unknown and i've never come across anything remotely suspicious). As a novice computer user you may chose to not run unknown software. By default your system is set up to not allow this so there is nothing you have to do.

Contrary to what Geeks on Hugs is telling you, Mac OS X does indeed have a basic malware scanner. It is not a feature that is directly accessible to the user, and works a bit differently than every other malware scanner out there. Gatekeeper, which has been mentioned here, is entirely separate, and provides a different method for helping to protect you against malware.

The anti-malware scanner in Mac OS X is called XProtect. When you download an application (or any other kind of executable code), it is automatically "quarantined," so that when you open it you're asked if you really want to do that. I'm sure you're very familiar with this aspect of Mac OS X if you have ever downloaded any apps from outside the App Store. What you don't know, though, is that each time you try to open a new app, that app is checked by XProtect. If it is identified as malware, you will not be allowed to open it, and will be warned that it's malware.

At this time, there is no known malware that can infect a properly up-to-date Mac. All current malware will be blocked by one or more methods.

For more information, see my Mac Malware Guide.

(Fair disclosure: I may receive compensation from links to my sites, TheSafeMac.com and AdwareMedic.com.)

No, OS X does not come with any built in virus protection

That is a common misconception.

I do know that Norton and Mcafee are both available for OS X.

Both are examples of garbage that should not be installed on any Mac.

Thank you for the info, I was not aware of that.

Apparently XProtect is available as of OS X 10.6 Snow Leopard:

About the "Are you sure you want to open it?" alert (File Quarantine / Known Malware Detection) in OS X - Apple Support

I guess it updates definitions with OS updates? I know Apple caps OS versions for computers as they age so if malware definition updates come via OS updates what happens as a Mac ages? In other words if someone's Mac runs Snow Leopard and can't be updated further how would the definitions get updated? My iMac is late 2012 and came with Mountain Lion. I've been able to update to Mavericks and then Yosemite. I wonder how much further I will be able to update my OS.

Thanks again!

I stand corrected, thanks!

Geeks on Hugs wrote:

I guess it updates definitions with OS updates?

Nope, it updates silently in the background, unless you have disabled automatic installs of security updates. Even Snow Leopard is still getting XProtect updates when necessary.