Windows – Starting executables in alternate data streams

Information stored in actual file streams will be lost. (Streams from sysinternals.com is a utility that allows you to view streams and optionally, delete them.) The kinds of files I believe you're talking about (photos, videos, etc.) store their metadata as part of the file, not in streams, so you'd be safe moving them around between different file systems. A simple test to determine whether data will be lost is burn them to a CD using Windows, as opposed to some other software. You don't have to actually burn the CD, just drag the file(s) in question to the CD Drive in "My Computer," or "Computer." If there are streams present, Windows will warn you that you may lose some data by copying them to CD.

I believe that in practice, streams are rarely used. Internet Explorer uses a stream to mark files that came from the Internet when you download. If you right-click on a downloaded file and choose "Properties," you'll notice a button that reads "Unblock." This button is triggered by the presence of a stream named ":Zone.Identifier:$DATA". Clicking the "Unblock" button deletes the stream. The stream will contain something like:

[ZoneTransfer]
ZoneId=3

You can view the contents of the stream by using something like:

more < "somefile.zip:Zone.Identifier:$DATA"

Alternate Data Streams in NTFS Applies to

* Microsoft Win32 Application Programming Interface, when used with:
      o Microsoft Windows NT Advanced Server 3.1
      o Microsoft Windows NT 4.0
      o Microsoft Windows NT 3.51 Service Pack 5
      o Microsoft Windows NT 4.0
      o Microsoft Windows 2000 Standard Edition
      o the operating system: Microsoft Windows XP

Very small ADS (Alternate Data Streams) are also added within Internet Explorer (and now also other browsers) to mark files that have been downloaded from external sites: *they may be unsafe to run locally and the local shell will require confirmation from the user before opening them. When the user indicates that he no longer wants this confirmation dialog, this ADS is simply dropped from the MFT entry for downloaded files.

Resource from Wikipedia