Mountain Lion enables you to set notification alerts to remind you of upcoming birthdays, tasks, meetings and other important events you might have in your calendar.
If you are more of a visual person and would like to organize your folders and files using different colors, than check it out how to use color labels in Mac OS X.
If you want to make a clean install of the new OS X Mavericks or even the older versions of Mac OS X, than I strongly suggest you to create a bootable OS X key or a drive.
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 experience an Mac OS X program to freeze and you cannot exit it by clicking quit or using a keyboard shortcut, you can always force it to quit using the Activity Monitor.
Mac OS X Moutain Lion and its Safari web browser sharing options allow you to share and send any web page vie email as a PDF attachment in a matter of two clicks.
