Turning on two-factor authentication wherever possible is still the best way to increase security online

Two-factor authentication works whenever you enter your username and password into a service, a numerical code is sent via text message or through an app to a second device, usually your smartphone. Entering this numerical code then authorizes your login.

So who offers it? Most email services and social media sites like Microsoft, Yahoo, Google, Facebook and Twitter have two-factor authentication available. To turn it on, just explore each site's settings page or app.

Many more sites offer this feature, so check when signing up to add this all-important layer of extra security. And yes, you still need to have a strong password—"password" just isn't going to cut it anymore. MORE