How to choose between SQL and NoSQL

SQL databases offer structured, ACID-compliant storage with strong consistency and complex querying capabilities through JOINs, but face challenges with horizontal scaling. NoSQL databases provide flexible schemas, horizontal scalability, and high performance for specific access patterns, trading strong consistency for eventual consistency. The choice depends on requirements: use SQL for transactional systems requiring data integrity (banking, e-commerce), and NoSQL for high-scale, flexible systems (social feeds, real-time analytics, IoT). Key considerations include consistency needs, scaling patterns, query complexity, and data structure flexibility.