Helm is a package manager for Kubernetes that allows for defining, installing, and upgrading Kubernetes applications called charts. Charts contain templates for Kubernetes manifest files and Helm uses a client-server model where the Helm client communicates with the Tiller server running inside the Kubernetes cluster. Key Helm commands include initializing Tiller, searching for charts, installing charts, upgrading charts, and deleting charts. Charts are organized directories that contain templates for Kubernetes resources and a Chart.yaml file.