What is Docker and Docker Container?

Perhaps you’re wondering what Docker is. Certainly, it’s a hot topic in cloud computing, one that people are finding ample job opportunities with skills in it. But if you don’t know what Docker is used for, you’ll never be able to cash in on these opportunities. Don’t fret – we’re here to fill you in.

What is Docker?

Plainly put, Docker is an open-source technology used mostly for developing, shipping and running applications. With it, you can isolate applications from their underlying infrastructure so that software delivery is faster than ever. Docker’s main benefit is to package applications in “containers,” so they’re portable for any system running the Linux operating system (OS) or Window OS. Though container technology has been around for a while, the hype around Docker’s approach to containers has moved this approach to the mainstream as one of the most popular forms of container technology. 
The brilliance of Docker is that, once you package an application and all its dependencies into a Docker run container, you ensure it will run in any environment. Also, DevOps professionals can build applications with Docker and ensure that they will not interfere with each other. As a result, you can build a container having different applications installed on it and give it to your QA team, which will then only need to run the container to replicate your environment. Therefore, using Docker tools saves time. In addition, unlike when using Virtual Machines (VMs), you don’t have to worry about what platform you’re using – Docker containers work everywhere.

What is Docker Container?

Now, your intrigue about Docker containers is no doubt piqued. A Docker container, as partially explained above, is a standard unit of software that stores up a code and all its dependencies so the application runs fast and reliably from one computer environment to different ones. A Docker container image is a lightweight, standalone, executable package of software that has everything you need to run an application – code, runtime, system tools, system libraries, and settings.

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.

The Benefits of Docker Containers

Docker containers are popular now because they have Virtual Machines beat. VMs contain full copies of an operating system, the application, necessary binaries, and libraries - taking up tens of GBs. VMs can also be slow to boot. In contrast, Docker containers take up less space (their images are usually only tens of MBs big), handle more applications and use fewer VMs and Operating Systems. Thus, they’re more flexible and tenable. 
Additionally, using Docker in the cloud is popular and beneficial. In fact, since various applications can run on top of a single OS instance, this can be a more effective way to run them. 
Isolation and Throttling

Another distinct benefit of Docker containers is their ability to keep apps isolated not only from each other but also from their underlying system. This lets you easily dictate how an allocated containerized unit uses its system resources, like its CPU, GPU and network. It also easily ensures data and code remain separate.


A Docker container runs on any machine that supports the container’s runtime environment. You don’t have to tie applications to the host operating system, so both the application environment and the underlying operating environment can be kept clean and minimal.

You can readily move container-based apps from systems to cloud environments or from developers’ laptops to servers if the target system supports Docker and any of the third-party tools that might be used with it.


Most business applications consist of several separate components organized into a stack—a web server, a database, an in-memory cache. Containers enable you to compose these pieces into a functional unit with easily changeable parts. A different container provides each piece so each can be maintained, updated, swapped out, and modified independently of the others.

Basically, this is the microservices model of application design. By dividing application functionality into separate, self-contained services, the model offers an alternative to slow, traditional development processes and inflexible apps. Lightweight, portable containers make it simpler to create and sustain microservices-based applications.

Why You Should Learn Docker

Obviously, Docker is important – and its prevalence in the job market is incredible. A recent search on LinkedIn revealed 28,941 jobs across the country are available. With cloud and Docker becoming more linked every day, that demand will only grow. Thus, you need to have Docker tools to have a wonderful future in DevOps. 

It’s easy to learn Docker, too. You can begin with the basics and take the Docker In-Depth Training Course. In it, you’ll gain in-depth knowledge of Docker, a containerization tool, and understand how to create your own flexible application environments by using Docker Compose. You’ll also create your own WordPress site with Docker and define multi-container application environments, among other things. Cool, no? 

However, if you really wanna master Docker and be a DevOps star, opt for certification in the field. Take Simplilearn’s DevOps Course. You’ll walk away a master of many: This will prepare you for a career in DevOps, the fast-growing field that bridges the gap between software developers and operations. You’ll become an expert in the principles of continuous development and deployment, automation of configuration management, inter-team collaboration and IT service agility, using modern DevOps tools such as Git, Docker, Jenkins, Cucumber, Ansible, TeamCity, and Nagios. Imagine that! You’ll learn to explain the types of version control systems, continuous integration tools, continuous monitoring tools, and cloud models. You’ll also describe the importance of cloud in DevOps, use of AWS in DevOps, and deploy your private Kubernetes cluster. You will even set up a test-driven development framework with Junit 5 and a behavior-driven development framework with cucumber. Don’t wait any longer. Now that you know what Docker is used for, learn it! 

About the Author

Shivam AroraShivam Arora

Shivam Arora is a Senior Product Manager at Simplilearn. Passionate about driving product growth, Shivam has managed key AI and IOT based products across different business functions. He has 6+ years of product experience with a Masters in Marketing and Business Analytics.

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