You Better Know

Following the release of Red Velvet's fourth extended play Rookie in February, SM Entertainment confirmed through news outlet on June 23, 2017 that the girls would be releasing their first summer release and had recently finished filming a music video.[1] After revealing both the group's image and video teasers, the song was released digitally with its parent album on July 9, 2017 and physically on July 10, 2017.

The song's production was handled by Becky Jerams, Pontus Persson and Kanata Okajima. Described as a "warm EDM" song, "You Better Know" was produced composed in the key of A major, with a tempo of 120 BPM.[2][3] Featuring energetic synths and "soaring electrified hook", the song's uplifting lyrics, which were written by Lee Seu-ran of Jam Factory, JQ and Choi Ji-hye, encourage listeners to "get ready" and "not letting go of the moment being".[4][5]

Upon its release, the song has become a fan-favorite track and received positive reviews from critics. While Lee Gi-seon of IZM magazine chose the track as one of the EP's highlights, Chase McMullen of The 405 website said that the song "slows things down only to build to anthemic chorus".[6][7] Furthermore, Chester Chin from Star2 praised the song's public-friendliness and presentation of Red Velvet's "dual concept of sweet and sassy", which made the song "an energetic synergy" for K-Pop.[4] In a separated top 25 songs by Red Velvet from Billboard magazine, the song appeared at number fourteen on the list and was noticed for "its foray" into the EDM genre, including "uplifting" lyrics like, “There’s a world that’s been waiting for you as you are.”[8]

Due to the massive success of the lead single "Red Flavor" and the song's commercial success, a special clip of the song was uploaded onto the official SMTOWN channel on July 27, 2017 as a gift to fans. The music video, titled "The Red Summer Vacation", uses a shortened version of "You Better Know" and features clips of the members having fun together during their vacation. It has since received more than 1.5 million views, as of November 2017. As part of the EP promotion, "You Better Know" was performed along with the title track during their first promotion week. The shortened version was first performed on SBS Inkigayo on July 9, then Mnet M Countdown and KBS Music Bank. An EDM remix of the song was performed during the group's first concert "Red Room", and later the group performed the song live during their attendance at 2019's The Fact Music Awards. The EDM remix was performed again during the first two nights of their third concert, titled "La Rouge" in November 2019.

After its digital release, the song quickly entered the real-time top ten of many Korean digital charts. The song debuted at number fourteen and number five on Gaon Digital Chart and Gaon Download Chart for the week of July 15, 2017, becoming their ninth top-twenty song and their highest charting entry for an album track to date.[9] With almost 120,000 downloads, "You Better Know" is currently their best selling album track, surpassing the achievement of "Oh Boy" (2015), an album track for their first studio album The Red.[10][11] In addition, it debuted at number twenty-one on the re-established Billboard K-Pop Hot 100 for the week of July 17, 2017, the highest peak position for an album track of the group.[12] It also charted at number seventy-three on the July issue of the monthly Gaon Digital Chart.[13]