A browser engine, also known as a rendering engine or layout engine, is a core component of a web browser that processes and renders web pages. It is responsible for interpreting the HTML, CSS, and other web technologies used in a web page and displaying the context appropriately on the user's screen.

The browser engine takes the raw HTML markup and parses it to understand the structure and elements of the web page. It then processes the CSS stylesheets associated with the page to determine how each element should be styled and positioned. The engine also executes any JavaScript code on the page, which may dynamically modify the page's content or behavior.

The rendering engine then takes this information and performs the web page layout, determining the size, position, and image rendering, handling user interactions like clicks and scrolling, and managing the rendering of animation and transitions.

Different web browsers have their own rendering engines, each with its own implementation and characteristics. For example, Google Chrome and Opera use the Blink engine (a fork of the WebKit engine), Mozilla Firefox uses the Gecko engine, Microsoft Edge uses the Chromium engine, and Safari uses the Webkit engine.

The browser engine plays a critical role in determining how web pages are displayed and interacted with by users. Its performance, compatibility with web standards, and support for new and emerging technologies influence the overall user experience when browsing the web.