What are Containers and How Do They Work?

The term “container” refers to image files in a format defined by the Open Container Initiative (OCI) which was formed under the auspices of the Linux Foundation in 2015.

Containers package a single application and all required library dependencies in a single, standardized, and operating system-specific way for either Linux or Windows. The name container comes from the idea that the application itself, and all that is needed for it to run, is packaged in one isolated “storage unit” (box, suitcase, or if you will: container), which enables it to run independently from its environment reliably and robustly. A significant benefit of containerized applications is that they will run the same regardless of where they are deployed across development, testing, and production environments. They also use far fewer resources (disk, memory) than e.g. virtual machines, start and stop more quickly, and can therefore be much more densely packaged on the host hardware.

Key Components of the Container Technology Stack

• Container Images: A container image bundles an application with its libraries, dependencies, and configuration into a portable, executable unit. Images are typically built using Dockerfiles or similar tools that define how the image is assembled.
• Container Runtimes: Container runtimes like Docker and Podman are responsible for executing containers on a host system. They handle process isolation, networking, and resource management to ensure containers run securely and efficiently.
• Container Registries: Container registries such as DockerHub, Amazon ECR, or Azure ACR store and distribute container images across environments.

What Are Container Images?

Container images are technically archive files that in its turn contain a set of files that can be unpacked on demand. Each container image archive contains all files required to start an application including the application itself, any required system libraries, tools, configuration, and meta-data.

Container images are then executed on a container runtime which is a low-level component that knows how to unpack the container image and start the application inside it. Each container image runs in isolation from others running on the same host.

Key Differences Between Container Images and Traditional Software Packaging

Traditional software packaging methods have long been plagued by environment-specific matters and heavy resource usage. Containers solve many of these challenges by standardizing how applications are packaged, deployed, and operated. Here’s how container images compare to traditional methods:

What Are Container Registries?

When applications are packaged as container images they are usually published to container registries e.g. Amazon ECR, Azure ACR, or DockerHub. Container registries allow users to find and download versioned container images for execution on a local container runtime.

Container registries play a key role in modern CI/CD workflows. When developers push updated container images to a registry, automation tools like GitHub Actions, GitLab CI, or Jenkins can automatically trigger deployment pipelines. This tight integration enables teams to build, test, and roll out new versions of containerized applications rapidly and reliably across environments—from development to production.

Beyond convenience, container registries also contribute to security and stability. By managing versioned images, registries ensure traceability and allow teams to roll back to known-good versions when needed. Most container registries also support access controls, vulnerability scanning, and image signing—providing safeguards that are essential when running containerized applications in production.

The Evolution from Virtual Machines to Containers: Why the Shift Matters

Application teams have a history of struggling with how to package software applications in a way that allows them to run the same application across development environments (e.g. laptops), testing environments (e.g. lab servers), and production environments (e.g. in the cloud).

1. Challenges of Traditional Application Packaging

In traditional application packaging, developers often had to repackage or rebuild their applications separately for different operating systems—typically Windows. This repackaging effort led to environment inconsistency, where an application might work perfectly on one system but fail on another due to subtle differences in dependencies, file systems, or runtime behaviors. These legacy constraints made testing and deployment slower and more error-prone, especially as applications scaled across multiple environments.

2. How Virtual Machines Changed Deployment

Compared to virtual machines, containers offer a lighter-weight alternative by leveraging OS-level isolation instead of bundling a full operating system with each application. This makes containers highly portable within datacenters while significantly reducing the resource overhead and startup time. However, while virtual machines provide strong isolation and are ideal for running multiple operating systems on a single host, they come with limitations. Virtual machines are heavier, consume more CPU and memory, and take longer to provision—making them less agile than containers in scenarios where speed and resource efficiency are critical. The container vs VM trade-off often comes down to balancing performance with security and operational flexibility.

3. Why Containers Are More Efficient Than VMs

Containers made provisioning applications even faster and significantly reduced the amount of overhead resources.

4. Standardization & Automation with Containers

The container technology stack enables lifecycle automation for containerized applications—from versioning and deployment to monitoring and rollback. Developers can define application behavior declaratively, ensuring consistency across environments and simplifying upgrades or rollbacks with versioned container images. This developer-first process reduces manual intervention and supports continuous delivery practices, allowing teams to ship changes quickly and confidently. Combined with built-in telemetry and health checks, the container technology stack streamlines the entire application lifecycle.

How Containerization Solves Edge Environment Deployment Challenges

Deploying applications across distributed edge environments introduces challenges like inconsistent infrastructure, limited resources, and unreliable connectivity. Containerization addresses these by offering a lightweight, consistent, and portable execution format that works seamlessly across heterogeneous edge sites. With containers, edge application deployments become more predictable, repeatable, and resilient—key requirements for managing large-scale distributed systems.

1. Consistency with Containers Across the Edge

Containers follow the “build once, run anywhere” principle, meaning the same containerized application can run reliably across different edge devices without modification. This consistency eliminates environment drift and simplifies debugging, testing, and updating applications at the edge—regardless of differences in hardware or OS versions.

2. Containerization and CI/CD Pipelines in Edge Computing

In edge computing, containers enable automated CI/CD pipelines by packaging applications into versioned images that can be built, tested, and deployed with minimal human intervention. This approach supports faster iterations and more reliable rollouts across edge sites, making it easier for development and operations teams to manage updates at scale.

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