Clef is secure two-factor authentication that allows you to log into your site without a password. Instead, you install the Clef app on your smartphone and Clef replaces the login page with a Clef wave–you launch the app and scan the wave on your screen with your smartphone's camera.
Here's a quick little introductory video:
Clef is installed as a plugin by default on all Wordpress installations on the Emory Domains server starting spring 2015. You can disable the plugin if you prefer the traditional username and password login, but we encourage you to give Clef a try. If you are not using a different, unique password for every site that you access and if your passwords are not sufficiently complex, then Clef is more secure and it's probably much easier to use than the traditional method.