🚖 1. Requirements ✅ Functional Requirements User can book a ride Driver can accept/reject ride Show real-time location tracking Calculate fare Payments (cash / online) Ratings & reviews ⚡ Non-Functional Requirements High availability (app should always work) Low latency (fast ride matching) Scalable (millions of users) Real-time updates (location tracking) 🏗️ 2. High-Level Architecture Main Components: Client Apps Rider app Driver app Backend Services API Gateway Ride Service Matching Service Pricing Service Payment Service Notification Service Databases User DB Driver DB Ride DB External Services Maps (Google Maps) Payment Gateway 🔄 3. How Ride Booking Works Step-by-step flow: User enters pickup & drop location Request goes to Ride Service Matching service finds nearby drivers Driver gets notification Driver accepts ride Ride starts → live tracking begins Ride ends → fare calculated → payment 📍 4. Driver Matching (Core Logic) This is the most important part. How it works: Divide map into grids (Geohashing) Find drivers in nearby grids Send request to closest drivers first Technologies: Redis (for fast location lookup) Kafka (for real-time events) 🧠 5. Database Design (Simple) Users Table user_id name phone Drivers Table driver_id location availability Rides Table ride_id user_id driver_id status fare 📡 6. Real-Time Location Tracking Driver app sends location every few seconds Backend stores it in Redis (in-memory) Rider app fetches updates via: WebSockets (best) or Polling 💰 7. Pricing System Base fare Distance fare Time fare Surge pricing (high demand → high price) 🔔 8. Notifications Push notifications (Firebase) SMS fallback ⚙️ 9. Scaling Techniques Load Balancer Microservices architecture Caching (Redis) CDN for static content Horizontal scaling 🔐 10. Security JWT Authentication HTTPS Secure payment handling 🧩 Bonus (Advanced Features) Ride pooling (shared rides) AI-based surge pricing Fraud detection Driver ranking system 🧾 Simple Architecture Diagram (Text) User App → API Gateway → Ride Service → Matching Service → Driver App ↓ Database ↓ Notification Service 🎯 Interview Tip If interviewer asks this question: Start with requirements Then high-level design Then deep dive into matching system + scaling