The Browser system consists of two components, the Browser service and the datagram receiver.
The Browser service is the user-mode portion of the Browser system and is responsible for maintaining the browse list, sending the API requests, and managing the various browser roles that a computer can have.
The Browser service actually resides within the Service Controller process (Lmsvcs.exe) and can be found under \<winnt_root>\system32. The Browser service is located in the registry path under the following key.
\HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Browser
The datagram receiver is the kernel-mode portion of the Browser system and is simply a datagram and mailslot receiver. It receives directed and broadcast datagrams that are of interest to the Windows NT Workstation and Windows NT Server services. The datagram receiver also provides kernel-level support for the NetServerEnum API, support for remote mailslot reception (second-class, datagram-based, mailslot messages), and the request-announcement services.
In Windows NT 3.5 and later, the datagram receiver is implemented in the Windows NT redirector (Rdr.sys). In Windows NT 3.1, there is a separate driver, Browser.sys, for the datagram receiver.