What is the functionality of the rendering engine in a web browser?

The rendering engine in a web browser is responsible for converting HTML and CSS into a visual representation that users can see and interact with on their screens. When a web page is loaded, the rendering engine takes the HTML markup, which structures the content, and the CSS, which styles that content, to create the visual layout of the page. This process involves parsing the HTML and CSS, constructing a Document Object Model (DOM) tree, and then applying styles and layouts to generate the final visual output.

The rendering engine also plays a crucial role in managing the rendering pipeline, which involves tasks such as layout (determining where elements should be placed on the page), painting (drawing the elements), and compositing (composing layers for rendering a final image on the screen). By effectively executing these tasks, the rendering engine ensures that users experience web content in an organized, visually appealing, and functional manner.

Other options present different functionalities associated with web browsers but do not align with the specific role of rendering engines. For instance, processing user input is a function of event handling, handling network requests pertains to the browser's networking components, and managing system resources is more about the overall operating system interface and performance management than the rendering process.