DevOps Dictionary

Docker is a platform for building, packaging, and running applications in containers—lightweight, isolated environments that bundle the app with its libraries and configuration so it behaves the same across machines. It solves the “works on my machine” problem by standardizing the runtime from a developer laptop to CI and production. At a high level, you describe the environment in a Dockerfile, build it into an immutable image (a versioned snapshot), then run that image as a container that shares the host operating system kernel while keeping processes and files separated using OS isolation features.

With Docker, teams get repeatable builds and predictable deployments; without it, releases often depend on manual server setup, environment drift, and harder-to-debug production failures. This gap exists because containers capture the application’s dependencies and execution context in a portable artifact rather than relying on each host to be configured correctly.