Why are there directories called Local, LocalLow, and Roaming under \Users\<username>?

Question

I have a workstation running Win2008 that's logged in an AD domain and I have a dual boot with Ubuntu Linux. When running Linux, I'd like to be able to use the same Thunderbird profile I use under Windows, so I pointed Thunderbird to use a profile I found under:

\Users\(myname)\AppData\Local\Thunderbird\Profiles

Turns out it was not the correct profile -- it had the right configuration, but the Inbox was an old version. I eventually found out the correct path was:

\Users\(myname)\AppData\Roaming\Thunderbird\Profiles

What's the rationale behind those different places to store application data?

Answer 1

Roaming is the folder that would be synchronized with a server if you logged into a domain with a roaming profile (enabling you to log into any computer in a domain and access your favorites, documents, etc. Firefox stores its information here, so you could even have the same bookmarks between computers with a roaming profile.

Local is the folder that is specific to that computer - any information here would not be synchronized with a server. This folder is equivalent in XP to C:\Documents and Settings\User\Local Settings\Application Data.

LocalLow is the same folder as local, but has a lower integrity level. IE8, for example, can only write to the locallow folder (when protected mode is on).

This document from Microsoft (downloads a .doc file) has a long explanation for what these three folder areas are and how they are used, as well as the changes implemented between XP and Vista (Windows 7 retains the Vista structure).

It is one of a series of documents in the Windows Vista Step-By-Step Guides for IT Professionals.