Netlify CMS is a static site CMS system that can be easily integrated with almost any static site generator, marking the end of an era where static sites were defined by their lack of dynamic content and user interactivity. This guide will walk you through setting up Netlify CMS in both local and online environments, starting with installing and configuring your own copy of the jekyll-netlify-cms template. The process involves creating a local repository, cloning it, and setting up the web configuration for the CMS system in the config.yml file. To set up the local environment, you'll need to download the netlify-git-api server that corresponds to your OS, add it to your path, and run specific commands to install Jekyll 3.0.0 with the jekyll-sitemap plugin. You'll also create Netlify CMS users, start the Netlify CMS server locally, build and watch your site, test the system, and then deploy it to a production environment on Netlify. The online environment involves connecting your GitHub repository, configuring settings, building your site, registering a new application, setting up GitHub API access, and trying out Netlify CMS.