This means that you can customize your browser with the features that are most important to you. Think of extensions as ways of adding new superpowers to what the browser can already do.
These superpowers can be mighty or modest, depending on your needs. For example, you might install a currency converter extension that shows up as a new button next to your browser’s address bar. Click the button and it converts all the prices on your current web page into any currency you specify. That’s helpful if you’re an avid backpacker who does most of your travel planning and booking online. Extensions like these let you apply the same kind of functionality to every web page you visit.
Browser extensions can also act on their own, outside of web pages. An email notifier extension can live on your browser toolbar, quietly check for new messages in your email account and let you know when one arrives. In this case, the extension is always working in the background no matter what web page you’re looking at — and you don’t have to log in to your email in a separate window to see if you have new messages.
When browser extensions were first introduced, developers often had to build them in unusual programming languages or in heavy-duty mainstream languages like C++. This took a lot of work, time and expertise. Adding more code to the browser also added to security concerns, as it gave attackers more chances to exploit the browser. Because the code was sometimes arcane, extensions were notorious for causing browser crashes, too.
To discover new extensions, check out your browser’s extensions gallery. You’ll see thousands of extensions that can help make browsing more efficient or just plain fun — from extensions that let you highlight and scribble notes on web pages while you’re doing research, to those that show nail-biting, play-by-play sports updates from your browser’s interface.