There are only limited copies of the first pressing of the album which sold out just in weeks. The first press includes "No.1 (Original Version)", "My Sweetie (Original Version)", and "Listen to my Heart (Big Chorus Version)". Later pressings of the album contain "No.1 (Music Video Version)" and "My Sweetie (Corrected Version)" (featuring a slightly amended ending).

The album debuted at #1 in the Korean Top 50 Monthly Chart with initial monthly sales of 232,400 in April 2002 and stayed at #1 the next 4 months. No.1 placed #2 on the list of the best-selling albums in Korea for 2002, with reported sales of 544,853 that year.

In a case spanning 13 years, Universal Music Korea and songwriter Kim Young Ah were locked in a lawsuit regarding the proper lyrics writer credit for the album's title track.

In 2002, Kim was asked to write the lyrics for “No. 1” and was paid 2 million won (approx. 1,800 USD) from SM Entertainment after the song was accepted. Shortly afterwards, SM signed a music copyright licensing contract with Universal Music Korea. Since the song was not registered with the Korea Music Copyright Association prior to the contract, Universal Music Korea registered “No. 1” in 2003. However, they listed the songwriter/lyrics writer for the song as Sigurd Rosnes (Ziggy) and the original copyright holder as Saphary Songs.

In 2011, Kim requested to the Korea Music Copyright Association that they delay payment of royalties to Universal Music, and in 2012, she filed the lawsuit for confirmation of being the lyrics writer for the song.

On July 6, 2015, the South Korean Supreme Court ruled that in Kim's favor. Besides getting officially credited as the song's lyrics writer, she will be receiving 45 million won (approx. 40,000 USD) in royalties, as well as 5 million won (approx. 4,400 USD) in compensation for her psychological distress due to the issue.

Promotional songs are in bold.

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Wikipedia