WinDbg is a multipurpose debugger for the Microsoft Windows computer operating system, distributed by Microsoft. Debugging is the process of finding and resolving errors in a system; in computing it also includes exploring the internal operation of software as a help to development. It can be used to debug user mode applications, device drivers, and the operating system itself in kernel mode. Like the better-known Visual Studio Debugger it has a graphical user interface (GUI), but is more powerful and has little else in common.
WinDbg can be used for debugging kernel-mode memory dumps, created after what is commonly called the Blue Screen of Death which occurs when a bug check is issued. It can also be used to debug user-mode crash dumps. This is known as post-mortem debugging.
WinDbg can automatically load debugging symbol files (e.g., PDB files) from a server by matching various criteria (e.g., timestamp, CRC, single or multiprocessor version) via SymSrv (SymSrv.dll), instead of the more time-consuming task of creating a symbol tree for a debugging target environment. If a private symbol server is configured, the symbols can be correlated with the source code for the binary. This eases the burden of debugging problems that have various versions of binaries installed on the debugging target by eliminating the need for finding and installing specific symbols version on the debug host. Microsoft has a public symbol server that has most of the public symbols for Windows 2000 and later versions of Windows (including service packs).
Recent versions of WinDbg have been and are being distributed as part of the free Debugging Tools for Windows suite, which shares a common debugging back-end between WinDbg and command line debugger front-ends like KD, CDB, and NTSD. Most commands can be used as is with all the included debugger front-ends.