Message Queues Explained: RabbitMQ vs Kafka vs SQS — When to Use What

Why Message Queues? Imagine Service A needs to send emails after a user signs up. If it calls the email service directly: What if the email service is down? The signup fails. What if it's slow? The user waits. What if 10,000 users sign up at once? Everything crashes. A message queue solves all three problems. Service A drops a message in the queue and moves on. The email service picks it up when it's ready. Core Concepts Producer → Queue → Consumer The basic pattern is simple: Producer publishes