"Rendering" in this context is turning an abstract representation of the content of your page (or state of your application) into HTML (either as bytes delivere

"Rendering" in this context is turning an abstract representation of the content of your page (or state of your application) into HTML (either as bytes delivered in an HTTP response from a server, or as DOM nodes created by JavaScript on the client). For Hacker News, "Server Rendering" is taking the top 25 stories, creating a large string containing all the HTML tags, then serializing that to a byte stream. A hypothetical "Client Rendering" alternative to HN might be downloading a JSON chunk containing the data about the top stories, then using a JavaScript framework to create DOM nodes in the user's browser that create the same document client-side.