Netlify CMS is an open-source solution that helps bloggers stay consistent with their content creation by providing a streamlined blog setup and integration with GitHub as a backend, which integrates directly with Netlify's Authentication Provider feature. To set up Netlify CMS on a Middleman blog, you need to create an admin folder in the public folder, add an index.html file and a config.yml file, and configure the collections and fields for the CMS. The CMS allows users to create, edit, and update posts via their web browser, and automatically makes GitHub commits when saving a post, which can be ideal for continuous deployment from GitHub to Netlify. Additionally, Netlify CMS offers features such as creating an editorial workflow that creates a Pull Request to view content changes and preview on a deploy preview.