Docker

Docker is an open-source platform that automates the deployment of applications inside lightweight, portable containers. It packages software with its dependencies, config, and runtime into images that can run consistently across different environments, from development to production. This approach aims to improve reproducibility, scalability, and isolation.

The core components include the Docker Engine, a client-server architecture consisting of a daemon (runs on host), a command-line interface, and a REST API. Images are built using recipes called Dockerfiles, which specify steps to assemble an image. Containers are runnable instances created from images. Docker Hub and private registries store and distribute images. Docker adheres to the Open Container Initiative standards for container images and runtimes, allowing compatibility with other tools.

The runtime relies on Linux kernel features such as namespaces and cgroups for isolation, and on a container runtime such as runc. The architecture enables layering of images, efficient storage via copy-on-write, and virtual networking between containers. Orchestration tools, notably Kubernetes and Docker Swarm, provide multi-host deployment and management.

Docker was initially released in 2013 by dotCloud, later evolved into a major ecosystem with Docker, Inc., and became central to modern DevOps practices. It popularized containerization for software development and continuous integration, influencing cloud-native workflows and microservice architectures.

Typical use cases include environment standardization, CI/CD pipelines, scalable services, and reproducible testing. Benefits include fast startup, lightweight isolation, and portability; limitations involve learning curve, security considerations, image management, and the complexity of large-scale orchestration.