The album's title is a wordplay on "noisy" and "no easy", and conveys the idea of the group making a loud impact on the world with their music.

The fourteen-track album spans the musical genres hip hop, EDM, pop, R&B, and rock, and includes the lead single "Thunderous", and earlier releases "Wolfgang" and "Mixtape: Oh".

Stray Kids uploaded the video "Step Out 2021", which describes the group's accomplishments in 2020 and plans for 2021—including a second studio album—.through their social media channels on January 1, 2021.

[9][10] Before the album announcement, in early July, Stray Kids released SKZ Camp Song: Howl in Harmony, a five-episode camp-type online program that documents the group's song-creation process and the making of music videos for them.

[21] Bang Chan, the group leader, told several South Korean news outlets; "[Noeasy] means that we want to leave a loud impact on the world with our music".

[23] The album's first four tracks are described as hip hop and EDM songs with aggressive bass sounds to represent fighting, and to mock the group's critics and haters.

[23][24] Several other Korean and foreign songwriter-producers, including Versachoi, HotSauce, Hong Ji-sang, and Krysta Youngs, also contributed to the album.

[26][27] "Thunderous", the second track and the album's lead single, is a hip-hop[18] and trap[18] song that includes elements of Korean traditional music (gugak), brass instruments, and chuimsae.

[32][33] The song is based on an EDM sound;[32] its lyrics are about winning over past difficulties and future uncertainties while feeling refreshed and optimistic.

[24][30] "Sorry, I Love You", the mid-tempo R&B[33] sixth track expresses a feeling of guilt and regret for liking someone and potentially ruining a friendship.

[36][24] "Star Lost", the dance-pop,[33] soft rock[37] ninth track, is a "feel-good" song with a nostalgic composition[24][26] that calls on fans who feel alone to believe in themselves.

[30] The upbeat,[38] alternative R&B[39] tenth track was performed by Bang Chan and Hyunjin; "Red Lights" features a "wild" feeling created by "violent" string sounds and electric guitar, giving it a "ripened sexy charm".

[38] The summer-vibe, upbeat, dance-pop[40] eleventh track "Surfin'" which is sung by Lee Know, Changbin, Felix, is described as "like a glass of carbonated water" with tropical sounds and marimba beats and lyrics about how having occasional little adventures can heal the soul and mind, allowing one to keep one's lives on track and not solely focus on work.

[5][6][43] Stray Kids released Noeasy on August 23, 2021, on CD in both limited-edition and standard versions and download, and on streaming platforms.

The jewel case version, which features a member's solo cover, contains a CD-R, a sticker, and a randomized photo card.

The trailer was directed by Lee Hye-sung and produced by Sushivisual;[54] it has a superhero theme and shows the members transforming into avenger corps against the ear-shaped "sound monster" by inventing technology and weapons, and brainstorming strategies in an apocalyptic world.

[63][28][64] The complete track list of Noeasy was announced on August 12, 2021, with "Thunderous" as the album's lead single, and the previous releases "Wolfgang" and "Mixtape: Oh".

The group gave the debut performances of the sub-unit tracks "Red Lights", "Surfin'", and "Gone Away" as a medley alongside "Thunderous" at the 2021 The Fact Music Awards on October 2.

Writing for Rolling Stone India, Divyansha Dongre said Stray Kids "keeps their identity intact as they reflect on hate directed towards their artistry", which is "centered around a powerful message of self-expression".

[18] Tamar Herman from South China Morning Post said the album "offers a lot of different styles to suit listeners and finds its strength in the group's creativity and storytelling", and that "Stray Kids have grown with each release".

[27] Chu Seung-hyun from Seoul Economy Daily wrote Noeasy is "full of unique bold and energetic appearance".

[124] Crystal Bell of Teen Vogue described the album as "more than noise", and complimented the group, saying they were able to "perfect their ability to make even the quiet parts unabashedly loud, showing us how to live with the noise—not run away from it".

[92] Upon its release, Noeasy debuted and peaked at number one on the thirty-fifth and thirty-sixth weeks of the South Korean Gaon Album Chart for the issue dates of August 22–28, and August 29–September 4, respectively,[146] becoming the group's fifth number-one album on the chart after Clé 1: Miroh, Clé: Levanter, Go Live, and In Life.

[90] Its tracks "Cheese", "Thunderous", "Domino", "Ssick", "The View", "Sorry, I Love You", "Red Lights", and "Wolfgang" simultaneously charted in the top 25 in the World Digital Song Sales.

[89][161] The album entered several national charts in Australia (fourteen),[162][163] Austria (twelve),[164] Belgium (both Flanders (thirteen),[165] and Wallonia (five)[166]), Croatia (thirty-four),[167] Denmark (three),[168] Finland (five),[169] Germany (sixty-four),[170] Hungary (five),[171] Lithuania (twenty-two),[172] the Netherlands (eighteen),[173] Norway (twenty-seven),[174] Poland (six),[175] Spain (sixty-seven),[176] and Switzerland (ten).