Google Prompt is a fast second step authentication option on iOS and Android. Whenever a login attempt is made on your Google account Google Prompt sends a login confirmation to the Google app on your phone. You open the app (via push notification) and tap “Yes” to confirm a login attempt is valid (or “No” to deny a login attempt).
This login method is quite a bit faster than using an authenticator app. I use Authy which even with its widget in the notification centre takes some time to copy the number into the field. I like Google Prompt for its speed and simplicity. The slight downside is that it requires your phone to have a live internet connection to use. This is only a slight downside because if you are signing into a Google service somewhere chances are that you have an internet connection available; with some exceptions. But Google Prompt works parallel to the other second step options available including an authenticator app, so in the absence of an internet connection on your phone you still have offline options to fall back on. Head into your Google 2 step verification settings to set it up.
From a security perspective it is hard for me to say whether this is a better or worse method than an authenticator app. I understand the methodology behind authenticator apps, but not this one. That said, I trust Google with my information and I trust them to have built a reliable and safe second step with Google Prompt. Furthermore I trust that they will be on the ball enough to keep it safe. I say this because of the numerous articles and security updates that are the result of contributions that Google has made to tech security worldwide.
In summary Google Prompt is a system I am prepared to trust and it makes my login process a great deal more streamlined whilst maintaining its integrity. I recommend this for anyone wanting the benefits of 2 step authentication with a bit of a faster workflow.