I disagree. The operative phrase here is "by default". Which implies that there is some "non-default" option. The relevant question posed by the GP was this: "I

I disagree. The operative phrase here is "by default". Which implies that there is some "non-default" option. The relevant question posed by the GP was this: "Is Apple really restricting you to install only app store and Gatekeeper verified apps?" That question is answered by the phrase "by default". Not entirely unambiguous, so why not take a moment to look in to it. On the very first page of Google search results for "os x gatekeeper" is the official Apple page, with the screenshot of the preference panel: http://www.apple.com/macosx/mountain-lion/security.html http://www.apple.com/macosx/mountain-lion/security.html That's 30 seconds of looking for anyone capable of typing two terms in to Google.