Docker vs Kubernetes
Docker builds container images and runs them on a single host. Kubernetes is an orchestrator: it schedules containers (built with Docker or any OCI-compliant tool) across a cluster of machines, restarts them when they crash, load balances traffic between replicas, and rolls out new versions with zero downtime. They are not competitors, Kubernetes usually runs containers that Docker (or Buildah/Podman) built.
Docker
Kubernetes
Use Docker when
You are shipping a small app, a side project, or a single service that fits comfortably on one machine.
Use Kubernetes when
You are running many services that need to scale independently, survive node failures, or be deployed by multiple teams.
Start with Docker to learn containers. Reach for Kubernetes once you actually have a fleet to manage, not because it looks impressive on a resume.
Study this on the roadmap