One of Drupal's most powerful, yet least documented features is the ability to run multiple sites from a single installation. This allows the modules, core code, databases, and hardware to all be maintained and upgraded centrally. How does this work? What are the best ways to implement this type of a setup? What are the various advantages and disadvantages of this setup? Lullabots John VanDyk and James Walker have had a lot of experience creating multisite Drupal installations. They'll share their experiences and insights.