Explain the differences between Docker and Kubernetes systems, their purpose, and how they are used together or separately.

Docker is a platform for creating, distributing, and running containers. Containers allow packaging an application with its dependencies into an isolated environment, ensuring portability and consistent operation across different machines.

Kubernetes is a container orchestration system that manages deployment, scaling, and maintenance of containerized applications across a cluster of servers.

Main differences:

• Docker handles the creation and running of individual containers.
• Kubernetes manages many containers, distributing them across nodes, ensuring fault tolerance and automatic scaling.

Usage:

• Docker can be used alone for local development and testing.
• Kubernetes is typically used in production environments for managing complex applications composed of many containers.

Usually, Docker and Kubernetes are used together: Docker creates containers, and Kubernetes manages their lifecycle in the cluster.