What does it do?
Selenium controls an actual web browser — Chrome, Firefox, whichever — programmatically, clicking buttons, filling in forms, and scrolling pages the same way a human would with a mouse and keyboard. Because it drives a real browser rather than just reading raw page code, it can handle websites that only show their content after JavaScript runs, which trips up simpler tools. It was originally built for software testing, letting developers automatically check that a website’s buttons and forms still work after a code change. Over time, people also started using it to automate repetitive browser tasks and scrape sites that would otherwise be invisible to simpler tools.
See it in action
This code opens a real Chrome browser window, visits a webpage, reads its main heading text, and then closes the browser.
from selenium import webdriver
from selenium.webdriver.common.by import By
driver = webdriver.Chrome()
driver.get("https://example.com")
heading = driver.find_element(By.TAG_NAME, "h1")
print(heading.text)
driver.quit()Why would a non-developer care?
Modern websites rely heavily on dynamic content that only appears after scripts run in your browser, which means a huge amount of a normal site’s content simply isn’t visible to tools that only read the raw underlying code. Selenium matters because it sees the page the way you do, after everything has loaded and rendered. That’s what makes automated testing of real websites, and scraping of JavaScript-heavy ones, actually possible.
Real-world examples
Selenium has been the backbone of web application testing for two decades, used by companies of every size to make sure a website still works correctly after every code deployment before real users see it. It’s also widely used to automate repetitive browser-based busywork, like filling out the same form on a government website hundreds of times. Without it, most companies would still be manually clicking through their own websites before every release to check nothing broke.
Who uses it
Quality assurance engineers testing websites automatically, and anyone automating tasks on sites that require real browser rendering.
How it compares to alternatives
Playwright, built more recently by former members of the team behind Chrome’s automation tooling, is generally faster and considered easier to write reliable tests with, and it’s been steadily taking market share from Selenium. Selenium’s advantage is its age and enormous existing ecosystem of tutorials, integrations, and enterprise adoption. Puppeteer and its Python cousin Pyppeteer cover similar ground but are limited mostly to Chrome-based browsers.
Fun fact
Selenium is named as an inside joke about mercury poisoning — its main early competitor was a commercial testing tool called Mercury Interactive, and selenium is a known antidote to mercury poisoning.