What is containerization? – Docker and Podman for beginners

One of the most important technologies in modern software development and operations is containerization, which allows applications to run in isolated, portable, and quickly deployable environments. While virtualization was previously the standard for running isolated workloads, container-based solutions have become the new industry norm—especially in the world of DevOps, CI/CD, and cloud-native systems.

In this article, we’ll explain in a clear and practical way:

• what containerization is,
• how Docker and Podman work,
• what the basic terms mean (image, container, volume, network),
• how to launch containers,
• the advantages and limitations of the technology,
• and what beginners should watch out for.

1. What is containerization?

Containerization is a type of software virtualization technology that enables packaging an application together with all its dependencies, configurations, and file systems into a container. This container is an isolated runtime environment that shares the host’s operating system kernel but has its own process and file system namespace.This means:

• applications always run in the same environment,
• the “it works on my machine” problem is eliminated,
• faster deployments and scalable operations are possible,
• lower resource usage compared to traditional virtual machines.

2. Container vs. Virtual Machine (VM)

Containers are not the same as virtual machines, but in many scenarios, they can replace them. Key differences include:

Thus, containers are faster, lighter, and more efficient, although they provide less isolation.

3. Docker fundamentals

Docker is the most popular and widely used container runtime, allowing you to build, run, and manage containers.

Key terms:

• Dockerfile: text file that defines how an image is built
• Image: a template used to launch containers
• Container: a running instance of an image
• Volume: persistent data storage for containers
• Network: container-to-container communication

Example:

docker run -it ubuntu bash

This command launches an Ubuntu container and opens an interactive shell.

4. Podman: the rootless Docker alternative

Podman is a container management tool that is Docker-compatible but more secure: it does not require root privileges to run.

Advantages:

• runs as a non-root user
• no central daemon (daemonless)
• integrates with systemd
• full CLI compatibility with Docker

Example:

podman run -it alpine sh

This launches an Alpine Linux container in interactive mode.

5. Why is containerization useful?

• Platform independence: same image can run anywhere (Windows, Linux, cloud, edge)
• Fast deployment: can start in seconds
• Easy distribution: push/pull from Docker Hub
• Version tracking: image history, rollback options
• Automation: integrates well with CI/CD pipelines

6. FAQ – beginner questions

1. Do containers save changes made inside them?No, unless you use a volume or commit the container as a new image.2. Can I run GUI applications in containers?Yes, but requires X11-forwarding or VNC.3. Can I use Docker on Windows?Yes, with Docker Desktop.4. What happens if I stop a container?All data is lost unless stored in a volume.

7. The future: Kubernetes, OCI, and AI containerization

The future of containerization is closely tied to scalable and automated infrastructure:

• Kubernetes: container orchestration, scaling, clustering
• OCI (Open Container Initiative): open standards for containers
• AI & ML containers: quick deployment of GPU-accelerated environments

Summary

Containerization is no longer just for DevOps engineers or cloud providers—it’s accessible and easy to use for anyone. Thanks to Docker and Podman, users can easily create fast, portable, and secure environments—whether on a local laptop or a server on the other side of the world.