This chapter summarizes the basic concepts related to the most targeted and widely used Windows operating system. The chapter explains Windows architecture and authentication process along with different Windows operating system tools including Windows management instrumentation command-line (WMIC), recycle bin, msinfo32, netsh (network shell), Windows services console, Windows registry, event viewer, NBTSTAT (NetBIOS over TCP/IP Status), system file checker, group policy editor, Windows firewall, Windows task manager, MSCONFIG utility, netstat (network statistics) utility, Attrib command, diskpart utility, etc. The chapter provides details of Windows powershell, an integrated scripting environment (ISE) for executing the commands at runtime as well as for developing and testing PowerShell scripts along with net commands and netsh commands. These tools are useful for diagnosing and testing the security level or condition of existing Windows installation. The Windows virtual machines created as part of experimental setup discussed as in first chapter of this book can be used to exercise the windows commands and utilities mentioned in this chapter.