It’s one of those phrases you often come across in stories about technology and hacking. But while “two-factor authentication” (or “2FA” for the tech geeks) sounds complicated, it really isn’t. It’s an extra security feature that’s relatively easy to set up—and a very good way to keep hackers out of your email and social media accounts.
The idea is that anytime one of your Internet accounts—such as Facebook, Gmail, or Amazon (AMZN)—detects an unfamiliar computer, it will ask you to provide an extra temporary password before you can log-in. You can see examples in the video above.
You don’t have to remember that extra password. Instead, Google (GOOGL) or Facebook (FB) (or any other site where you’ve turned on two-factor) will send it you in the form of a text message. You just enter the extra password once on the new computer, and you’re logged in as usual.
But if it’s a hacker or someone else trying to log-in from a strange computer, they won’t be able to get into your account—even if they know your password.
The nice thing about two-factor authentication is it provides a lot of security without much inconvenience. After all, most of us use the same handful of devices (maybe a home computer, a cell phone, and a laptop) to login to Facebook and email, and so on. It’s only once in a while you’ll be using a new computer and have to enter the extra password sent by text message.
Get Data Sheet, Fortune’s technology newsletter.
Also note that, if for some reason you don’t want to receive the extra password by text message, you can have sent it you by email or a phone call. But text messages are the easiest option.
So if you want to turn on two-factor authentication, the best way to go about it is to decide which of our accounts is most important to you. While you can set it up for dozens of sites on the Internet, that could be a slog. It’s probably best to just think “Wouldn’t it be terrible if someone got into my ______ accounts” and set it up for that. (For me, priority accounts would include Gmail and Twitter (TWTR). Sites like Pinterest, LinkedIn, and Amazon are also good candidates for 2FA).
Once you’ve chosen the accounts for which you want extra-security, go to the website in question, log in, and find the page with security settings. Or you can just Google the name of the site and “two-factor authentication.” (Facebook calls it “login approvals,” but it’s the same thing.)
From there, it’s pretty easy. There will be a page where you tell the website you want to turn on two-factor authentication, including how you want to receive the extra password—once again, text message is easiest—and you’re good to go. The nice thing is, once you’re set up, you don’t need to bother with it again unless you log-in to a new computer. And you’ll be much safer.