Docker

Docker is a platform for building and running containers: lightweight, portable packages that include an app plus the libraries and settings it needs. “It works on my machine” becomes “it runs in this container everywhere.”

Developers use Docker for local setups, CI/CD builds, and consistent deploys to hosting or the cloud. It pairs well with microservices (one container per service) and with Kubernetes when you need to manage many containers at scale. A Dockerfile describes how to build the image; that image is what you ship.

A real-life example of Docker

A team builds a WordPress site. On one laptop PHP is 8.1; on another it’s 8.2; staging is missing an extension. With Docker, everyone runs the same WordPress + PHP + database stack from one definition — and production matches it. We’ve used that pattern on client projects; see How to Use WordPress with Docker.

Docker does not replace good web architecture or a clear CI/CD pipeline — it makes the runtime predictable so those pieces fail less often for “environment” reasons.