Welcome back to Billboard's weekly video show "Real-Time Rewind," which recaps the past week's hottest action on the new Billboard Real-Time Twitter Charts --Trending 140 and Emerging Artists -- and the news that's driving the action. Joe Levy is back in the studio on Episode 27, which features Gwen Stefani, Ariana Grande, and a roundup of this year’s GRAMMY nominations.

VIEW THE REAL-TIME CHARTS: TRENDING 140 | EMERGING ARTISTS

So what was happening on the Real-Time Charts this week?

Gwen Stefani released an emoji-filled music video for her new single "Spark the Fire" on Monday Dec. 1. The track debuted at No. 25 on the Trending 140, and soon climbed to No. 1  after Stefani and Pharrell Williams performed it on The Voice.

Ariana Grande released her Christmas song, "Santa Tell Me," on Nov. 24. It topped the Trending 140 the day after its release date, continuing Grande's streak of No. 1 charting titles. "Problem," "Break Free," "Bang Bang," "Love Me Harder" and "All My Love" have all reached No. 1 on the Trending 140.

And last, GRAMMY nominations began to impact the Real-Time charts as soon as nominations rolled in the morning of Friday, Dec. 5. Eric Church was an early beneficiary, surging to the top as soon as Best Country Album was announced. John Legend reached No. 1 after the Best Pop Vocal Solo Performance nomination was announced, in which he's nominated for "All of Me." When the Best Rock Song nomination came around, Beck’s track "Blue Moon" battled it out with Ryan Adams' "Gimme Something Good" for the top spot.

The Trending 140 chart measures the acceleration of conversation around artists and their music, while the Emerging Artists chart measures the volume of tweets around new artists and their songs.