Introduction to Selenium

Understand what Selenium is, its architecture, Selenium 4 features, how it compares to other tools, and when to use it.

What is Selenium?

Selenium is the most widely adopted open-source framework for automating web browsers. It supports multiple programming languages, browsers, and operating systems — making it the industry standard for web UI test automation.

Selenium 4 — What's New

Selenium 4 is a major upgrade built on the W3C WebDriver standard. Key improvements include:

• W3C WebDriver Protocol — Direct browser communication, no JSON Wire Protocol translation layer
• Relative Locators — Find elements relative to other elements (above, below, near, toLeftOf, toRightOf)
• Chrome DevTools Protocol (CDP) — Network interception, geolocation mocking, console log capture
• New Window/Tab API — Open new tabs or windows programmatically
• Improved Selenium Grid — Docker support, fully distributed mode, GraphQL queries

Selenium Architecture

Selenium WebDriver communicates directly with the browser through a browser-specific driver (ChromeDriver, GeckoDriver, etc.). Your test code sends commands via the WebDriver API, the driver translates them into browser-native commands, and the browser executes them.

When to Use Selenium

Selenium excels when you need cross-browser testing, multi-language support, a large ecosystem of integrations, or when your team already has Java/Python expertise. It's the right choice for enterprise-scale test automation where flexibility and community support matter.

Tools We'll Use

• Java — Maven for dependency management, TestNG as the test runner, Selenium 4.x WebDriver
• Python — pip for packages, pytest as the test runner, Selenium 4.x bindings

// Java — Selenium 4 Quick Start
// Requires: Maven + Java 17+
// Selenium 4 uses W3C WebDriver protocol natively

import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;

public class IntroSelenium {
    public static void main(String[] args) {
        // Selenium 4 — no need for System.setProperty!
        // Selenium Manager auto-downloads the correct driver
        WebDriver driver = new ChromeDriver();

        try {
            driver.get("https://www.selenium.dev/");

            System.out.println("Title: " + driver.getTitle());
            System.out.println("URL: " + driver.getCurrentUrl());
            System.out.println("Browser: Chrome via Selenium 4");

            assert driver.getTitle().contains("Selenium");
            System.out.println("Selenium 4 is working!");
        } finally {
            driver.quit();
        }
    }
}

# Python — Selenium 4 Quick Start
# Install: pip install selenium

from selenium import webdriver

# Selenium 4 — Selenium Manager handles driver automatically!
# No need for webdriver_manager or manual driver downloads
driver = webdriver.Chrome()

try:
    driver.get("https://www.selenium.dev/")

    print(f"Title: {driver.title}")
    print(f"URL: {driver.current_url}")
    print("Browser: Chrome via Selenium 4")

    assert "Selenium" in driver.title
    print("Selenium 4 is working!")
finally:
    driver.quit()