What is Selenium and what problems does the suite solve?

Selenium is an umbrella project rather than a single framework. WebDriver is the browser automation API, Grid runs sessions across machines and browsers, and Selenium Manager resolves drivers and browser binaries. Language bindings exist for Java, Python, JavaScript, C#, Ruby and Kotlin.

• WebDriver sends commands to a real browser through the W3C WebDriver protocol
• Grid routes sessions to registered browser nodes for scale and cross-browser coverage
• Selenium Manager discovers or downloads a matching driver at runtime
• Selenium IDE records and replays simple flows, mainly for exploration and prototyping

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

public class SmokeTest {
    public static void main(String[] args) {
        WebDriver driver = new ChromeDriver();
        try {
            driver.get("https://example.com");
            System.out.println(driver.getTitle());
        } finally {
            driver.quit();
        }
    }
}

Selenium does not provide a test runner, assertions, API testing, reporting or test data management. Production suites combine it with TestNG or JUnit, an assertion library, an HTTP client such as RestAssured and a reporter such as Allure.