Understanding an application's critical path is crucial for ensuring its reliability and functionality, especially in complex systems with numerous components and dependencies. The critical path comprises essential components and workflows that enable the application to perform its core functions; if any of these components fail, the application cannot serve its primary purpose, such as allowing purchases in an e-commerce platform. Application mapping helps identify these components and their interdependencies, which is vital for building resilience and preventing costly outages. Chaos Engineering is employed to test and improve the reliability of the critical path by deliberately introducing failures and observing system responses, as demonstrated with an e-commerce website's CartService and its dependency on Redis. By focusing on the critical path, teams can proactively mitigate risks, enhance user experience, and prevent revenue loss from unexpected outages.