"Happy" is the fourth digital single by Taeyeon. It was released on May 4, 2020.
It was originally set to be released on March 9, 2020 but was postponed due to the passing of her father.
A summer version live video of the song was released on June 26, 2020 through the SM STATION YouTube channel. The song was later included on her fourth Korean mini album What Do I Call You.