Windows 7: AppData folder not visible in windows explorer

Question

I am somewhat new to Windows 7. I am running a foreign language version of Windows 7 (not sure if this matters or not). Anyways, when I use cmd to run a command prompt environment and

C:\Users\MyUserNameHere> dir

I don't see the folder named AppData.

When I do the same thing and go and check this out from the windows explorer application I also cannot see the AppData folder. However, when I

C:\Users\MyUserNameHere> cd AppData

I can cd to this folder. It is as though this folder is somehow hidden.

So, my questions are:

1. What is this folder for, i.e., what is its purpose in Windows 7? I see some installations install stuff under this folder and others do not. Why?

2. What is the difference between the three directories contained therein: Local, LocalLow, and Roaming? Do they have different purposes?

3. Can I "unhide" this hidden AppData folder so that I can navigate to it with more ease in the windows explorer.exe application?

4. Aptana Studio 3 installed itself under the AppData\Local directory whereas webcam shots taken with skype are found under AppData\Roaming. Why this choice of directories? (this question is just a special case of 2.)

Thank you for clarifications,

I also would like to be pointed to a book detailing this sort of things for Windows 7 so that I may be able to better use the OS if you don't mind suggesting a link or book.

Answer 1

1. The folder is used for applications to store any user data, such as settings or cache files.

2. See this site for a good explanation.

3. You can un-hide the folder by turning off the "hidden folders" feature under [Edit>Folder Options] (press the alt key to see the menus). Or see the above link for further info.

4. I expect that the program is storing the shots in roaming so that if you were using a networked pc (such as on a domain in a work place) the images would be able to travel from PC to PC when you logged on and off.