Containerization (Docker)

Containerization packs an app with its runtime so it starts the same on any machine that has the runtime.

A container bundles application code, runtime libraries, system tools, and settings into a single lightweight unit. Unlike virtual machines, containers share the host OS kernel, making them small and fast to start. Docker is the dominant container platform.

It provides tools to build, ship, and run containers, eliminating the "it works on my machine" problem. When developers package an app as a Docker image, any team member or automated system can pull and run it. Deployment becomes a single command.

Environment differences that used to cause bugs vanish. Enterprises adopt containers because they work with orchestrators like Kubernetes, which automatically starts, stops, and scales thousands of containers based on demand. This enables microservice architectures, batch processing, and machine-learning model serving.

In cloud environments where you pay for compute time, the fast startup of containers means you pay only for actual usage. Containers share the host kernel and isolate the process. That is lighter than a VM and is what Kubernetes schedules.