Hystrix is a library developed by Netflix that helps manage the interactions between distributed services in a microservices architecture. It provides a way to prevent cascading failures by isolating points of access to remote services, allowing applications to fail gracefully when a service is unavailable. The main features of Hystrix include circuit breaking, which stops requests to a failing service, and fallback mechanisms, which provide alternative responses when a service is down. This enhances the resilience and stability of applications, ensuring they continue to function even when some components are experiencing issues.