How do message queues fit into microservice architectures?

Hey everyone, I'm trying to wrap my head around the best ways to integrate message queues into a microservices setup. We're looking at decoupling services and handling asynchronous tasks, but I'm wondering about the trade-offs. When does it make sense to introduce a queue like Kafka or RabbitMQ versus direct service-to-service communication or an event bus? What are your go-to patterns for managing dead-letter queues and ensuring message delivery guarantees in a distributed system?