Alternate Data Stream is the feature in NTFS which enables to store data or files without being listed in the directories. This feature enables NTFS partition to be compatible with other partitions like that of Mac's HPFS over the network. for example lets say that there are two text files namely Main.txt and attached.text
To create a ADS of a text file type the following command
echo > main.txt:attached.txt
now even if u delete attached.txt u can still view it by using the command
to add a exe file you must
to run the executable files type
Alternate data streams can also be used to store system information of the file. You can also add files to directories.