Can web apps have real-time data synchronisation?

Yes! Real-time sync enables instant updates across users and devices. Use cases include: collaborative tools (multiple users editing simultaneously), live dashboards (metrics update automatically), chat applications (messages appear instantly), booking systems (availability updates in real-time), delivery tracking (map updates as driver moves), stock/inventory (reflect purchases immediately), auction platforms (bids update live), and multiplayer features (interactive experiences). Technologies used: WebSockets (bi-directional communication), Firebase (real-time database), Pusher (managed real-time service), and Server-Sent Events (server pushes updates). Implementation considerations: conflict resolution (what happens when two users edit same data), connection management (handling disconnections gracefully), scalability (supporting many concurrent users), and battery impact (mobile devices). Real-time features transform user experience - updates appearing instantly feels magical compared to refreshing pages. Popular applications: Google Docs-style collaboration, Uber-style tracking, or Slack-style messaging. Real-time capabilities add complexity but deliver compelling experiences justifying the investment.