Docker is an open-source platform that automates the deployment and management of applications within containers. Containers are a lightweight and portable way to package software applications and their dependencies, making it easy to run the same application in different environments. Docker allows developers to build, ship, and run applications in a consistent and reliable way across different platforms and architectures.

One of the key features of Docker is its ability to provide isolation between applications and their dependencies. Each container provides a separate environment for the application to run in, with its own file system, network interfaces, and other resources. This makes it easier to manage dependencies and avoid conflicts between applications running on the same system.

Another important feature of Docker is its support for container orchestration. This allows developers to manage and scale their applications across multiple hosts and clusters, using tools like Kubernetes and Docker Swarm. With container orchestration, it's possible to automatically deploy and manage large-scale applications with minimal manual intervention.