Docker, originally a side project of Solomon Hykes at DotCloud, revolutionizes application deployment with its lightweight container technology, contrasting with traditional virtual machines by running applications in isolated environments that share the host OS kernel. Docker enables efficient resource management, portability across platforms, and supports a thriving community through Docker Hub for sharing and downloading containers. Additionally, tools like Docker Compose and Swarm facilitate the management and orchestration of multi-container applications across various cloud environments.