Isolated storage is a private file system managed by the .NET Framework. Like the standard file system, you can use familiar techniques (such as StreamReader and StreamWriter) to read and write files. However, isolated storage requires your code to use lesser privileges, making it useful for implementing least privilege. Additionally, isolated storage is private, and isolated by user, domain, and assembly.
When to use isolated storage:
Isolated storage is not always the best solution for storing persistent data. Isolated storage should not be used to store configuration and deployment settings, which administrators control. It is a good way to store user preferences, however - because administrators do not control them, they are not considered to be configuration settings.
If you require high encryption for your data, you can use isolated storage; but don’t rely on its security. Encrypt the data before writing it to isolated storage. Isolated storage should not be used to store high-value secrets, such as unencrypted keys or passwords, because isolated storage is not protected from highly trusted code, unmanaged code, or trusted users of the computer.
You can look up the System.IO.IsolatedStorage namespace to learn more about how you can leverage the feature in your .NET applications.