Volt is a Ruby web framework where your Ruby code runs on both the server and the client (via opal). The DOM automatically updates as a user interacts with the page. Page state can be stored in the URL, so bookmarks return to the same state.
Instead of syncing data between the client and the server via HTTP, Volt uses a persistent connection. When data is updated on one client, it is updated in the database and in any other listening clients (with no setup needed). Permissions and validations can be created to control how data can be updated.
Page HTML is written in a template language where you can put Ruby between {{ and }}. Volt uses data flow/reactive programming to automatically and intelligently propagate changes to the DOM (or any other code that wants to know when a value changes). When something in the DOM changes, Volt intelligently updates only the nodes that need to be changed.
In addition to the docs, a good way to get started is with the demo videos:
Check out demo apps: