Docker can be considered both software and a tool. As software, Docker is a platform that uses OS-level virtualization to deliver software in packages called containers. Containers are isolated from each other and bundle their own software, libraries, and configuration files. As a tool, Docker offers functionalities to build, manage, and distribute these containers effectively. So, Docker is software that provides a suite of tools for software engineers and system administrators to develop, deploy, and run applications in a consistent environment. Docker is often used in conjunction with cloud services like Amazon Web Services (AWS) or Microsoft Azure, enabling seamless deployment of web applications and leveraging the scalability of the cloud. It is widely used in backend development and project management, simplifying the deployment and management of web services and applications. Docker's command-line interface (CLI), which includes commands written in Bash, allows developers to interact with Docker and perform various operations on containers and images. Docker's open-source nature and support for various operating systems and frameworks make it a popular choice for software engineers across different domains, including Android app development, web application development, and data center management.