Portainer is a GUI tool that makes Docker easy to use, manage, support and scale. It provides a consolidated view of all containers across multiple Docker environments, including Kubernetes, Docker and Swarm. Portainer allows developers to deploy, manage and troubleshoot containerized applications without needing deep Kubernetes expertise. The document then provides step-by-step instructions to install Portainer on Linux, Windows and WSL/Docker Desktop. It also describes some of Portainer's key features for managing containers, images, networks, volumes and more through an intuitive web-based interface.