Kubernetes ImagePullBackOff -- container image not accessible

Pod stuck in ImagePullBackOff or ErrImagePull state. Container cannot start because the image cannot be downloaded.

Debug: kubectl describe pod NAME -- check Events section. Common causes: (1) Image name typo or wrong tag: docker.io/myapp:latest vs myapp:latest. (2) Private registry: need imagePullSecrets configured. kubectl create secret docker-registry regcred --docker-server=... (3) Image does not exist: verify with docker pull on local machine. (4) Rate limiting: Docker Hub limits anonymous pulls (100/6h). Use authenticated pulls. (5) Wrong architecture: pulling amd64 image on arm64 node. (6) Network: node cannot reach registry (firewall, DNS).

Kubernetes pulls images from registries at pod creation time. Any failure in authentication, network, or image availability prevents the container from starting.