Hystrix is a library that helps you build resilient and fault-tolerant applications. It’s designed to prevent your application from failing completely when one of its dependencies fails, by isolating and handling failures in a way that’s safe and doesn’t cause further damage.

To understand Hystrix, imagine you have an application that depends on a database. If the database goes down, your application would fail because it can’t access the data it needs to function. This is a common scenario in real-world applications, where there are multiple dependencies and components that can fail at any time.

Hystrix helps you handle such scenarios by introducing a layer between your application and its dependencies. This layer is called a circuit breaker, and it’s responsible for monitoring the health of the dependency and taking appropriate actions when it fails.