When you type a URL, such as www.example.com, into your browser, what actually happens? First, the browser would send a request to one of Example Corp's servers, which retrieves the resource requested (for example, an HTML file), and sends it back to the client:
The browser then parses the HTML, retrieves all the files the web page depends on, such as CSS, JavaScript, and media files, and renders it onto the page.
The browser consumes flat, one-dimensional texts (HTML, CSS) and parses them into tree-like structures (DOM, CSSOM) before rendering it onto the page.
This scheme is known as the client-server model. In this model, most of the processing is handled server-side; the client's role is limited to simple and superficial uses, such as rendering the page, animating menus and image carousels, and providing event-based interactivity.
This model was popular in the 1990s and 2000s, when web browsers were not very powerful. Creating entire applications with JavaScript...
