Kubernetes is a robust container orchestration system that manages the lifecycle of containers, enabling scalable, high-availability application deployments across multiple hosts or virtual machines. Within Kubernetes, ReplicaSets ensure fault tolerance and high availability by maintaining a specified number of operational pods, automatically creating new ones if any are deleted or crash. Pods, the smallest unit in Kubernetes, house containers but are not inherently fault-tolerant without a controller like ReplicaSet. The article details how to define and use ReplicaSets using YAML files, explaining their role in scaling applications and ensuring system resilience. Additionally, it touches on the installation of Kubernetes, MiniKube, and Docker, providing insights into the internal workings of ReplicaSets and highlighting their significance in creating scalable, fault-tolerant systems, while also suggesting Earthly as a tool for efficient and reproducible builds.