When copying a file that includes alternate data streams, what happens to the streams during the copying process?

Alternate Data Streams (ADS) are an NTFS-specific feature that allows additional named data streams to be attached to a file alongside its primary content. When copying a file with ADS to another NTFS-formatted volume, Windows preserves all associated streams exactly as-is. If the destination is a non-NTFS file system such as FAT32 or exFAT, the streams are silently dropped without an error or warning.

Windows does not automatically compress or encrypt alternate data streams using WinZip or any other algorithm during a standard file copy operation; streams are either preserved or silently discarded.

Alternate data streams are not universally removed during copying - they are only lost when the destination file system lacks NTFS support, and the primary file data is always copied regardless.

Windows does not generate an error message or warning when alternate data streams are lost during a copy to a non-NTFS destination; the loss occurs completely silently.