Reliability is crucial for software delivery teams, as IT outages can cost organizations up to $1 million per hour and damage reputations. Chaos testing, a component of chaos engineering, is a method used to improve software reliability by simulating failures and testing how applications respond to them. Originating at Netflix with the Chaos Monkey tool, chaos engineering has evolved to include a suite of tools that introduce various failure scenarios. Benefits of chaos testing include gaining insights into system operations, enhancing reliability by identifying flaws, and stress-testing incident responses. However, challenges include the necessity of having a clear hypothesis and model, the risk of unintended damages, and the importance of robust observability tools. Chaos testing has become integral to DevOps practices, with platforms like Gremlin and Chaos Mesh automating the process. These tests are particularly valuable in cloud-native systems, where microservices depend on each other, allowing developers to understand and improve system reliability in a controlled environment.