How does Selenium WebDriver work end to end?

There are four layers to reason about: your test code, the language binding, the browser driver, and the browser itself. The binding serialises commands, the driver translates them into browser actions, and the response travels back the same way. No test code runs inside the browser process unless you explicitly execute JavaScript.

• Your test runs in a JVM, Python interpreter or Node process
• The binding exposes methods such as findElement and click over HTTP
• The driver owns the browser process and the protocol session
• The browser renders the page and exposes DOM and navigation behaviour

import java.net.URL;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeOptions;
import org.openqa.selenium.remote.RemoteWebDriver;

WebDriver driver = new RemoteWebDriver(
    new URL("http://localhost:4444/wd/hub"),
    new ChromeOptions());
driver.get("https://example.com");
driver.quit();

When you call new ChromeDriver(), the binding starts chromedriver and creates a session. ChromeDriver then launches Chrome and holds the connection. Selenium Manager can locate or download chromedriver, which removes most manual driver setup but does not remove the driver process itself.