Headless Browser
A real browser running without a visible window. It loads pages and runs JavaScript exactly like Chrome does, but is driven by code rather than a mouse and keyboard.
Full Definition
A headless browser is a full browser engine — rendering HTML, executing JavaScript, managing cookies and sessions — that operates without a graphical user interface. Chrome/Chromium and Firefox both support headless mode. Automation frameworks like Playwright and Puppeteer use headless mode by default for speed, but also support headed mode when you need to debug visually or avoid headless-browser detection. Many anti-bot systems specifically look for headless browser tells (missing browser APIs, unusual navigator properties, absent plugins), which anti-detect browsers or stealth patches address.
