You are trying to install or open an app that didn't come from the Mac App Store but you got a message saying App can't be opened because it is from an unidentified developer. This is how you bypass it.
If you are tired and annoyed by the app requests and notifications your friends keep sending on Facebook, this is how you get rid of them without having to unfriend your friends.
You probably seen video where clips are playing in a title text and made you wondered how the heck to they do that. Well it's pretty easy to create the video in text effect with Adobe Premiere.
Morse code is a method of transmitting text information as a series of on-off tones, lights, or clicks that can be directly understood by a skilled listener or observer without special equipment.
You can add multiple desktops to the Mac OS X Mountain Lion by using Mission Control, formerly known as Spaces. Can be really useful if you are a busy multi-tasker.