With the release of this important security update, Apple's hands-off stance when it comes to updating its Web browser is changing. Over the past three years, Apple has often gone three months without so much as releasing a single security update for Safari.
Sophos's Naked Security blog also says that many of the security holes in the patch were found by Apple's in-house researchers. The most important issue that the update fixes is "drive-by download" vulnerabilities. Drive-by downloads are programs or code snippets that can be downloaded and run without the user's consent.
To see if you can download this update, click on the Apple icon on the far-left of the bar on top of your Mac, then click the "software update" button. You should see a list of all of the apps on your computer that need to be updated. Simply click the update button next to "Safari" if it's available. If it isn't available, then your browser is already up-to-date and secure.
Watch out, though, any pre-Snow Leopard versions of OSX don't support the latest version of Safari. You probably won't have to worry about your version of OSX unless your Mac computer is more than three years old. Luckily, Mavericks is a free download. You can find out more about updating to OSX Mavericks in my helpful tip.