container image
also: container image, Docker image, OCI image, image
A lightweight, standalone package containing an application, its dependencies, libraries, and runtime environment—everything needed to run the application consistently across different systems.
A container image is a read-only template that serves as the blueprint for creating and running containers. It includes the application code, system libraries, environment variables, and configuration files bundled together in a layered filesystem format.
Container images are typically built using a Dockerfile (for Docker) or similar specification. For example, a web application image might include a Linux base OS layer, Node.js runtime, your application code, and npm dependencies—all stacked together.
Images are stored in registries (like Docker Hub, Quay.io, or private registries) and can be pulled down and instantiated into running containers on any system with a container runtime like Docker or Podman. Multiple identical containers can be launched from the same image, ensuring consistency across development, testing, and production environments.