Process Explorer is a freeware computer program for Microsoft Windows created by Sysinternals, which was acquired by Microsoft Corporation. Process Explorer is a system monitoring and examination utility, similar to a souped-up version of Task Manager, and often can be used as the first step in debugging software or system problems when in the hands of an experienced software engineer. Process Explorer provides many unique features that can be used to empower the user of the product to track down problems. For example, it provides a means to list or search for named resources that are held by a process or all processes. This can be used to track down what is holding a file open and preventing its use by another program. Or as another example, it can show the command lines used to start a program, allowing otherwise identical processes to be distinguished. Or like Task Manager, it can show a process that is maxing out the CPU, but unlike Task Manager it can show which thread (with the callstack) is using the CPU information that is not even available under a debugger. Process Explorer works on Windows 9x/Me, Windows NT 4.0, Windows 2000, Windows XP, Windows Server 2003, Windows Vista. It also works on 64-bit versions of Windows.