How do I open the firewall port for SQL Server on Windows Server 2008?

Windows Firewall on Windows Server 2008 helps prevent unauthorized access to computer resources. However, if the firewall is configured incorrectly, attempts to connect to an instance of SQL Server may be blocked. To access an instance of SQL Server that is behind the firewall, you must configure the firewall on the computer that is running SQL Server. This article helps you open the firewall