(Also referred to as an SQL Server instance) Allows you to organize site databases. Use the default instance for use with Smart Interop Publisher, or you can create an instance dedicated for Smart Interop Publisher. See the Smart Interop Publisher Installation and Setup Guide.
Each SQL Server instance can host one or more site databases. Smart Interop Publisher requires you to create at least one site database.
See How do I organize my files? and Configure a site database.