# Kubernetes

URL: https://softwaredictionary.org/terms/kubernetes
Category: DevOps & Cloud
Last updated: 2026-09-29
Pronunciation: KOO-ber-NET-eez

In short: Kubernetes is an open-source system that automates deploying, scaling, and managing containerized applications across a cluster of machines.

## What is Kubernetes?

Kubernetes, often shortened to K8s, is a container orchestration platform. When an application runs as many containers across many servers, Kubernetes decides where each container runs, restarts containers that crash, scales them up or down with demand, and routes network traffic to them. It was originally created at Google and is now maintained by the Cloud Native Computing Foundation (CNCF).

Kubernetes is declarative: you describe the desired state in YAML files, such as 'run three copies of this web app', and Kubernetes continuously works to make reality match that description. Its key building blocks are pods (the smallest unit, one or more containers that run together), deployments (which manage copies of pods and roll out updates), and services (stable network addresses for a group of pods).

A good analogy is an orchestra conductor, which is where the word orchestration comes from. The musicians (containers) play the music, while the conductor makes sure the right number are playing, replaces anyone who stops, and keeps everything in sync. Major cloud providers offer managed Kubernetes services, so teams don't have to run the cluster's control plane themselves.

Kubernetes is often compared with Docker, but they solve different problems: Docker builds and runs individual containers, while Kubernetes manages many containers across a cluster. Kubernetes is powerful but complex, so small projects often do fine with simpler options such as Docker Compose, a platform as a service, or serverless hosting.

## Key takeaways

- Kubernetes orchestrates containers across a cluster of machines.
- You declare the desired state in YAML, and Kubernetes keeps it that way.
- Pods, deployments, and services are its core building blocks.
- It handles scaling, self-healing, rolling updates, and load balancing.
- K8s is short for Kubernetes: a K, eight letters, then an s.

## Example: A Kubernetes Deployment running three copies of an app

```yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: web
spec:
  replicas: 3 # keep three copies of the container running at all times
  selector:
    matchLabels: { app: web }
  template:
    metadata:
      labels: { app: web }
    spec:
      containers:
        - name: web
          image: example/web:1.0
```

## Frequently asked questions

**What is the difference between Docker and Kubernetes?**

Docker is used to build container images and run containers, typically on one machine. Kubernetes runs and manages many containers across many machines, handling scheduling, scaling, and recovery, and it can run images built with Docker.

**Why is Kubernetes called K8s?**

K8s is a numeronym: the 8 stands for the eight letters between the K and the s in Kubernetes. The name itself comes from the Greek word for helmsman or pilot.

**Do I need Kubernetes?**

Not always. Kubernetes pays off when you run many services that need automated scaling and high availability; for a single small app, a simpler hosting platform or Docker Compose is usually enough.

## Sources

- [Kubernetes documentation: Overview](https://kubernetes.io/docs/concepts/overview/)

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