This document provides an overview of the Domain Access module for Drupal, which allows building and managing multiple websites from the same Drupal installation and codebase. Key capabilities include: - Setting up add-on domains, parked domains, and domain aliases that point to the same Drupal install but have separate databases and settings. - Integrating a shared user authentication system so users can login to different sites using the same credentials. - Configuring domain-specific settings like theme, content, navigation menus. - Rewriting URLs and tying content visibility to the domain to present domain-specific experiences. - Providing tools for users to create and manage subdomains through a single site.