Cloud Native Architecture is an approach to designing and building applications that exploits the advantages of the cloud computing delivery model. It emphasizes:

1. **Characteristics:**
   - Scalability
   - Containerization
   - Automation
   - Orchestration
   - Microservices

2. **Key Principles:**
   - Design for automation
   - Build for resilience
   - Enable scalability
   - Embrace containerization
   - Practice continuous delivery

Microservices is an architectural style that structures an application as a collection of small autonomous services, modeled around a business domain.

Key characteristics:
1. **Independence:**
   - Separate codebases
   - Independent deployment
   - Different technology stacks

2. **Communication:**
   - API-based interaction
   - Event-driven
   - Service discovery

Example of a microservice API:
```yaml
openapi: 3.0.0
info:
  title: User Service API
  version: 1.0.0
paths:
  /users:
    get:
      summary: List users
      responses:
        '200':
          description: List of users
    post:
      summary: Create user
      responses:
        '201':
          description: User created
```

A service mesh is a dedicated infrastructure layer for handling service-to-service communication in microservices architectures.

Key components:
1. **Data Plane:**
   - Service proxies (sidecars)
   - Traffic handling
   - Security enforcement

2. **Control Plane:**
   - Configuration management
   - Policy enforcement
   - Service discovery

Example of Istio configuration:
```yaml
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: reviews-route
spec:
  hosts:
  - reviews
  http:
  - route:
    - destination:
        host: reviews
        subset: v1
      weight: 75
    - destination:
        host: reviews
        subset: v2
      weight: 25
```