Five reasons to use SharePoint 2013 communities for driving engagement: 1. SharePoint already has community features built-in for collaboration, contribution, communication and connectedness. 2. Communities can be flexibly configured using different site templates like community portals, sites or publishing sites. 3. Communities are easy to use with features like mobile access, simple administration and moderation tools. 4. Communities have simple administration including permissions, content approval, notifications and moderation tools. 5. Gamification features like badges and ratings can further increase participation and engagement.