"365" is a song by German music producer Zedd and American singer Katy Perry. It was released on February 14, 2019 along with its music video, directed by Warren Fu. The song reached number one in Bulgaria and Israel, and the top forty in twenty other countries.
In August 2018, Zedd was the opening act of Perry's Witness: The Tour in Australia and New Zealand. While on tour, the pair worked together on new music, although Zedd was unsure at the time if the collaboration would result in any material. In January 2019, there were rumors about the upcoming release of the song, which was eventually leaked. It was later registered with Universal Music Publishing Group in February, and the song then appeared registered on Shazam before being removed and re-added again. On February 13, Zedd and Perry began sending emojis to each other on Twitter before Zedd shared the trailer for the video.