Rendering, in the context of computer graphics, refers to the process of generating an image from a 2D or 3D model using computer programs. This can result in photorealistic or non-photorealistic images. When we talk about rendering in the context of web browsers, we often refer to the rendering engine, which is responsible for displaying the content of a website on the user’s screen.
A rendering engine, sometimes called a browser engine, plays a crucial role in rendering web pages. It handles the layout of the website, paints visuals, and manages animations. Essentially, it ensures that the elements on a webpage are displayed correctly on the user’s screen, providing the intended visual experience.
When we surf the web, several steps occur:
- Entering URL: We type a URL into the browser’s address bar.
- Parsing URL: The browser parses the URL to extract information like the protocol, host, port, and path, forming an HTTP request.
- DNS Lookup: The browser translates the human-readable host into an IP address through a DNS lookup.
- Opening a Socket: A socket is opened from the user’s computer to the IP address and specified port.
- Sending HTTP Request: The browser sends an HTTP request to the host.
- Server Processing: The server processes the request, launches the necessary plugins, and prepares an HTTP response.
- Receiving Response: The browser receives the response, parses the HTML, and builds a DOM tree.
- Fetching Resources: Additional requests are made for resources (images, stylesheets, JavaScript files) mentioned in the HTML.
- Stylesheet and JavaScript Processing: Stylesheets are parsed, and JavaScript is executed, updating the DOM.
- Rendering the Page: The browser renders the page on the screen based on the DOM tree and style information.
- Page Display: Finally, the user sees the rendered page on their screen.
Major web browsers use different rendering engines:
- Blink: Used in Google Chrome and Opera.
- WebKit: Used in Safari.
- Gecko: Used in Mozilla Firefox.
- Trident: Used in older versions of Internet Explorer.
- EdgeHTML: Used in older versions of Microsoft Edge.
- Presto: A legacy rendering engine for the Opera browser.