I'm not an expert, so take this with a grain of salt. Hopefully someone corrects me if I'm wrong, but.. "Static client" here doesn't refer to the user's brows

I'm not an expert, so take this with a grain of salt. Hopefully someone corrects me if I'm wrong, but.. "Static client" here doesn't refer to the user's browser. It refers to a front-end that serves web requests. It serves them statically, in that every URL maps to a static HTML file (with embedded javascript). Once the user receives that static HTML browser with embedded javascript, this then becomes the client. The javascript (run from within the user's browser now) communicates with a back-end or server, which the article describes as a "RESTful JSON API". It fetches JSON documents and uses the results to render HTML. "Render" here means "turn the backend data into HTML output". This all is in contrast with a more common approach to dynamic web-pages, in that every URL request prompts a dynamic process on the server to do some logic (fetch data from a database often, and parse and interpret request parameters) to render HTML which is then sent back to the user. Hope that helps.