Design Yelp or Nearby Friends

How will you store location data? Will you use latitude-longitude, geohashing, or a spatial index (e.g., R-Tree, QuadTree)?

How do you handle different types of proximity services - static (e.g., restaurants) vs dynamic (e.g., nearby friends or riders)?

What kind of caching would you implement for frequently accessed areas (e.g., popular cities)?

How will you rank and personalize results (e.g., by distance, rating, user preferences)?