This document is about technics of hiding objects, files, services, processes etc. on OS Windows NT. These methods are based on hooking Windows API functions which are described in my document ”Hooking Windows API”. Everything here was get from my own research during writing rootkit code, so there is a chance it can be written more effectively or it can be written much more easily. This also involve my implementation. Hiding arbitrary object in this document mean to change some system functions which name this object in the way they would skip its naming. In the case this object is only return value of that function we would return value as the object does not exist. Basic method (excluding cases of telling different) is that we would call original function with original arguments and then we would change its output. In this version of this text are described methods of hiding files, processes, keys and values in registry, system services and drivers, allocated memory and handles.