SQL Browser Service in SQL 2005

SQL Server Browser Service in SQL 2005 provides information about the SQL Server 2005 instances installed on a machine. It provides the instance name and version number for each instance of the database engine and analysis server engine installed on a system. Its counter part in SQL Server 2000 is SQL Server Resolution Service which operates on UDP Port 1434 and provides information about the SQL Server 2000 instances on a particular machine. SQL Server Browser service is instance insensitive and it gets installed with the first instance of a machine. When SQL Server Browser Service starts, it accumulate information about Port number, named pipes of all instances installed on the system from windows registry. The it begins to listen network request on UDP port 1434.

It is not necessary to have SQL Server browser running , if it is not running you can still connect to a instance of a system by providing protocol , ServerName/,PortNumber or named pipe directly in the connection string Eg. TCP:ServerName,1456. If you have only one default instance then SQL Server Browser does not have any significance, because default instance always listens to 1433.