Microsoft Authenticator is the new mobile application that replaces Azure Authenticator, Microsoft account app and all other enterprise and consumer authenticator apps for Android, IOS and Windows mobiles, published by Microsoft.
This new app can quickly and securely verify your identity online, for all of your accounts.
It provides Multi-Factor authentication for your personal, work, or school Microsoft accounts with notifications or one-time-passwords. Additionally, you can use this app to register your device with your company's Azure Active Directory and get seamless single-sign-on to mobile applications.
Later this year you'll also be able to use the app to unlock sign in to a device (Windows Hello), app, or website without a password
Watch this short video presented by Paul Blachar, Program Manager, Microsoft Identity division.