Windows 7 - What is the purpose of the AppData/Roaming folder?

I'm running Windows 7 x64 and noticed I was down to the last 7 GB of storage on my 120GB app disk. I've only got about 50 GB of apps so it looked like something was amiss. I did some poking around and discovered the Users/username/AppData/Roaming folder had 41 GB of stuff in it. 36 GB is in one folder, Adobe. I have Master Collection CS5, but the program files for all of it (stored in another folder, of course) only add up to about 15 GB. I'll post over in the Adobe forums but thought I'd ask here if anybody knows what this stuff is for? Thanks.

In XP this folder equals to
Documents and Settings\$USER$\Application Data

The main purpose is to store "Application-specific data, such as a custom dictionary for a word processing program. Application vendors decide what data to store in this directory", so "the data roams with the user wherever he or she logs on".

And "User data can include shortcuts to executable files, personal files, and user settings, such as a custom dictionary."

Regarding your case with Adobe, please use WinDirStat - Windows Directory Statistics
to check what file type is the majority of those big files.

Thanks for the pointer to WinDirStat. It helped me solve the problem by identifying hundreds of unnecessary files.