What Is Docker?

Docker is the world’s leading software containerization platform. Docker is a tool designed to make it easier to Deploy and run applications by using containers. Containers allow a developer to package upon applications with all of the parts it needs, such as libraries and other dependencies, and ship it all out as one package.

Docker Image

Are the basis of containers. An image is an ordered collection of root filesystem changes and the corresponding execution parameters for use within a container runtime.

  • An image typically consists of a union of layered filesystem stacked on top of each other.
  • An image doesn’t have state and te never changes.

Docker Hub

Is a centralized resource for working with Docker and its components it provides

  • Docker image hosting
  • User authentication
  • Automated images build and workflow tools, such as build triggers and webhooks.
  • Integration with Git hub and bit bucket.

Docker Registry

Registry is a hosted service containing repositories of images which responds to the registry API.

  • Default registry can be accessed using browser at Docker hub or using the Docker search command


A repository is a set of Docker images the repository can be shared by pushing it to a registry server.

  • The different images in the repository can be labeled using tags.

Basic Concepts


A Docker container image is a lightweight, standalone, executable package of software that includes everything needed to run an application like code, runtime, system tools, system libraries, and settings.

What Docker Can Do For You

Docker is the de facto developer standard for building and sharing apps that enable simplicity, agility and choice for software development across any infrastructure so that you can get your job done and Deploy your applications faster.

Docker for Developers

Today’s developers face a variety of languages, frameworks and architectures, as well as discontinuous interfaces between tools for each lifecycle stage, resulting in application development that is enormously complex. We simplify and accelerate workflows for developers with an integrated development pipeline and application components.


Docker provides developer-friendly, CLI-based workflow and makes it easy to build, share, and run containerized applications. Even your most complex applications can be containerized. You can build locally, Deploy to the cloud, and run anywhere.


Docker is easy to configure and helps you speed up your workflows. Deploy or undeploy your applications faster. Start and stop faster. Change or replace build images faster. Docker even accelerates the migration of applications from the data center to the cloud.


Docker offers you the broadest choice. Build, share and run applications across any combination of clouds, operating systems, languages and frameworks. Docker works with every cloud provider and supports Kubernetes for orchestration across hybrid architectures.

Docker Containers Are Everywhere: Linux, Windows, Data center, Cloud, Serverless, etc.

Docker container technology was launched in 2013 as an open source Docker Engine.

It leveraged existing computing concepts around containers and specifically in the Linux world, primitives known as cgroups and namespaces. Docker’s technology is unique because it focuses on the requirements of developers and systems operators to separate application dependencies from infrastructure.

Success in the Linux world drove a partnership with Microsoft that brought Docker containers and its functionality to Windows Server (sometimes referred to as Docker Windows containers).

Technology available from Docker and its open source project, Moby has been leveraged by all major data center vendors and cloud providers. Many of these providers are leveraging Docker for their container-native IaaS offerings. Additionally, the leading open source serverless frameworks utilize Docker container technology.

Package Software into Standardized Units for Development, Shipment and Deployment

A container is a standard unit of software that packages up code and all its dependencies so the application runs quickly and reliably from one computing environment to another. A Docker container image is a lightweight, standalone, executable package of software that includes everything needed to run an application: code, runtime, system tools, system libraries and settings.

Container images become containers at runtime and in the case of Docker containers – images become containers when they run on Docker Engine. Available for both Linux and Windows-based applications, containerized software will always run the same, regardless of the infrastructure. Containers isolate software from its environment and ensure that it works uniformly despite differences for instance between development and staging.

Docker containers that run on Docker Engine:

  • Standard: Docker created the industry standard for containers, so they could be portable anywhere.
  • Lightweight: Containers share the machine’s OS system kernel and therefore do not require an OS per application, driving higher server efficiencies and reducing server and licensing costs.
  • Secure: Applications are safer in containers and Docker provides the strongest default isolation capabilities in the industry.

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