What Is a Docker? Let’s Say you created an application, and that’s working fine in your machine.??????? Figure 1: App Working Fine   But in production it doesn’t work properly, developers experience it a lot. Figure 2: Not Working in Production   That is when the developer’s famous words are spoken Client: Your application is not working Developer: It works on my machine Figure 3: Client Developer   The Reason could be due to: Dependencies Libraries and versions Framework OS Level features Microservices That the developer’s machine has but not there in the production environment.   We need a standardized way to package the application with its dependencies and deploy it on any environment. Docker is a tool designed to make it easier to create, deploy, and run applications by using containers. Figure 4: Docker Icon   How does docker work? Docker packages an application and all its dependencies in a virtual container that can run on any server. Figure 5: Container   Each container runs as an isolated process in the user space and take up less space than regular VMs due to their layered architecture. Figure 6: Architecture   So, it will always work the same regardless of its environment. Credit Goes to @codechips