StatefulSets are used to manage stateful applications, providing guarantees about the ordering and uniqueness of Pods.

Key features:
1. **Stable Network Identity:**
   - Predictable Pod names
   - Stable hostnames

2. **Ordered Deployment:**
   - Sequential creation
   - Sequential scaling
   - Sequential deletion

Example of StatefulSet:
```yaml
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: web
spec:
  serviceName: "nginx"
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80
        volumeMounts:
        - name: www
          mountPath: /usr/share/nginx/html
  volumeClaimTemplates:
  - metadata:
      name: www
    spec:
      accessModes: [ "ReadWriteOnce" ]
      resources:
        requests:
          storage: 1Gi
```

DaemonSets ensure that all (or some) nodes run a copy of a Pod. As nodes are added to the cluster, Pods are added to them.

Use cases:
1. **Monitoring Agents**
2. **Log Collectors**
3. **Node-level Storage**
4. **Network Plugins**

Example of DaemonSet:
```yaml
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: fluentd-elasticsearch
spec:
  selector:
    matchLabels:
      name: fluentd-elasticsearch
  template:
    metadata:
      labels:
        name: fluentd-elasticsearch
    spec:
      containers:
      - name: fluentd-elasticsearch
        image: quay.io/fluentd_elasticsearch/fluentd:v2.5.2
```

Helm is a package manager for Kubernetes that helps you manage Kubernetes applications through Helm Charts.

Key concepts:
1. **Charts:**
   - Package format
   - Collection of files
   - Template mechanism

2. **Repositories:**
   - Chart storage
   - Version control
   - Distribution

Example of Helm Chart:
```yaml
apiVersion: v2
name: my-app
description: A Helm chart for my application
version: 0.1.0
dependencies:
  - name: mysql
    version: 8.8.3
    repository: https://charts.bitnami.com/bitnami
```

Istio is an open-source service mesh that provides a way to control how services communicate with one another. It includes:

1. **Traffic Management:**
   - Load balancing
   - Traffic routing
   - Fault injection
   - Traffic mirroring

2. **Security:**
   - Authentication
   - Authorization
   - Encryption
   - Mutual TLS

3. **Observability:**
   - Telemetry
   - Metrics
   - Tracing
   - Logging

Container Runtime Interface (CRI) is an API that allows container runtimes to interact with the container orchestrator. It includes:

1. **Image Management:**
   - Pulling images
   - Pushing images
   - Listing images
   - Deleting images

2. **Container Management:**
   - Creating containers
   - Starting containers
   - Stopping containers
   - Killing containers
   - Inspecting containers

3. **Container Runtime:**
   - Running containers
   - Pausing containers
   - Resuming containers
   - Executing commands in containers