Docker

Docker is an open-source platform that enables developers to automate the deployment, scaling, and management of applications within lightweight, portable containers. A container packages up an application's code along with all of its dependencies, such as libraries, system tools, and runtime environments. This creates a self-contained unit that can run consistently on any machine that has Docker installed. The core problem Docker solves is the 'it works on my machine' syndrome. Inconsistencies between development, testing, and production environments can lead to bugs and deployment failures. By containerizing the application, you create a standardized, reproducible environment that is identical everywhere. The process starts with a `Dockerfile`, which is a simple text file that contains a set of instructions for building a Docker 'image'. An image is a read-only template that contains the application and its dependencies. The `Dockerfile` specifies the base image to use (e.g., an official Node.js image), copies your application code into the image, installs any necessary dependencies (e.g., using `npm install`), and defines the command to run when the container starts. Once you have an image, you can run it to create one or more 'containers'. A container is a runnable instance of an image. This makes Docker an incredibly powerful tool for local development, continuous integration, and production deployment.