If you are using Finder in OSX, you will find that their files structure is too clean. In fact, most of the system folders and files are hidden from normal user. There are occasions in which you may need to access system file (e.g. edit host file). The following simple steps show you how to unhide/hide system files in OSX using Terminal.
With the recent announcement of free OS X Mavericks, many MacBook users will surely upgrade their OS without any hesitation. The easiest way is to just go to "Software Update" and download the 5GB+ installer and upgrade from there. Personally, I prefer to fresh install Mavericks as I have phobia since Windows era such that things will get slower the longer you use your current OS and the best solution is to start everything from fresh. With a flash card and a software tool, you can do so for Mavericks as well.