Appdata\Local Roaming LocalLow文件夹简介
自Vista及Win7开始，微软更改了原有的应用程序存储目录结构，（XP是Application Data）系统盘：用户\用户名\Appdata, 并分为Roaming, Local,及 LocalLow三个文件夹.
更改原因如下:
• 优化登录速度
• 根据使用安全级别分别访问不同文件夹
Windows 使用 Local及LocalLow文件夹存放非漫游的应用程序数据（类似注册表Local_machine）及一些空间占用大无法漫游的应用程序数据，而Roaming文件夹则用来保存可漫游的用户应用程序数据，如每个用户的个性化设置等。
The Roaming folder is to preserve user data. Imagine a company with 1000 workstations, and employee use different workstations each day. By roaming the user profile data (copy to server), the custom data is always available regardless of any workstation the employee uses.
The applications choose whether to save to local or roaming, and roaming is used by default by most applications, it acts as local to people not on a domain, and to people that are, their settings follow them.
Local is only typically used when explicitly preventing settings following a user across a domain. This will be usually due to size of the settings folder to prevent having to transfer gigabytes across a domain in cases such as cache. For example Chromium (web browser) uses local instead of roaming as it’s cache folder is within the user settings folder. Most other applications separate the cache and settings for this reason.
The naming of local and roaming is unfortunate, as most users at home aren’t on a domain and can easily be confused by such terms.
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. It is worth to remember that “Roaming” folder is synchronized with the server meaning bigger the size of roaming folder longer the time required to logon to a PC. The folder “Roaming” by design ensures that ONLY absolutely essential data like “Favorites” “Desktop” and “Documents” travel with the user thereby making it as 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 SettingsUserLocal SettingsApplication 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).
1、Local和Roaming之间的区别：Local 比较大，非漫游应用数据。Roaming 一般是漫游应用数据。
2、Roaming和locallow之间的区别：
roaming文件夹是Windows存放一些使用程序后产生的数据文件，如空间听音乐，登入的号码等而缓存的一些数据。
Appdata下有三个子文件夹local，locallow和roaming。
1、当解压缩包时如果不指定路径，系统就把压缩包解到local\temp文件夹下，存放了一些解压文件，安装软件时就从这里调取数据特别是一些制图软件，体积非常大，占用很多空间。
2、locallow是用来存放共享数据，这两个文件夹下的文件就用优化大师清理，一般都可以清理无用的文件。
3、roaming文件夹也是存放一些使用程序后产生的数据文件，如 空间听音乐，登入 的号码等而缓存的一些数据，这些数据优化大师是清理不掉的，可以打开roaming文件夹里的文件全选定点击删除，删除不掉的就选择跳过，不过当你再使用程序时，这个文件夹又开始膨胀，又会缓存数
