A machine running Microsoft Windows NT or Windows 2000 that is involved in supporting the functions of the Computer Browser service. The master browser for a domain is usually the primary domain controller (PDC) for that domain.
The master browser collects and maintains a list of available servers that have shared network resources in its domain. This list, known as the browse list, is created when individual servers announce their presence on the network by sending a server announcement to the master browser.
The master browser also collects and maintains a list of all Windows NT and Windows 2000 domains on the network. If the domain of a master browser spans several subnets, the master browser maintains only the browse list for its own subnet and one master browser will exist for each subnet in the domain.
Backup browsers obtain a copy of the browse list from the master browser. Backup browsers automatically contact the master browser every 15 minutes to request a copy of both the browse list and a list of domains on the network. The backup browser caches this list and distributes it to any client on the network that requests it.