Kustomize is a configuration management tool for Kubernetes that allows users to manage different environments like production and staging without altering the original application manifests. By using a kustomization.yaml file, Kustomize overlays provide a way to modify configurations and create environment-specific customizations without templates, facilitating debugging and performance comparisons. It is integrated with kubectl and can serve as a standalone tool or be used within a GitOps workflow, such as with ArgoCD, to automate deployments and maintain the desired state across environments. This integration allows continuous monitoring and updates based on changes in the Git repository, ensuring that Kubernetes deployments remain consistent with the specified configuration. The flexibility of Kustomize in managing configurations without a templating system is highlighted, making it a powerful choice for Kubernetes deployments while maintaining different settings for various environments.