To hide one file in another
The below trick can be used to hide one file in another. This will work ONLY on a NTFS file system and NOT in FAT.

1) Create a simple text file in notepad in any location from the command prompt:-
notepad originalfile.txt
2) Enter some text into it and save it. Check the file size using dir command.
3) Now create the stealth file using the command below:-
notepad originalfile.txt:hiddenfile.txt
4) Type some text into it which you want nobody to see or read. Save this file. Done!!!
5) Check the size of the file "originalfile.txt". It will be the same as you saw it in step 2. U will never see the file originalfile.txt:hiddenfile.txt or hiddenfile.txt anywhere in ur hard disk. It cannot be searched either. So basically it becomes ur supersecret file. Only u know abt it.

6) Anytime you want to edit this file, use:-
notepad originalfile.txt:hiddenfile.txt
and enter ur secret data into it which nobody can see