The song was written and composed by Nyoy Volante, who was her boyfriend at that time, and it was produced by Warner personnel Neil Gregorio.
"Someday" was well received by critics and became a commercial success, topping Philippine music charts for eight weeks.
International songwriters were hired, and Nina's boyfriend at that time, Volante, volunteered to work on the album.
Nina's vocal input on the song is described as "a simple, toned-down, near whispery volume evoking a hotel lounge-level of intimacy".
The same with the music, where the entire song was recorded using an acoustic piano as the only instrument, with no additional percussion or drums.
[5] "Someday" is considered to be the reason why Nina (the album) managed to reach Platinum by the Philippine Association of the Record Industry.
Rito Asilo of Inquirer Entertainment praised the song in a review, saying "The introspective, traffic-stopping 'Someday', that boasts of a rich melody and Nina’s emotive panache".
[10] Music publicist Oliver Oliveros gave a review of the song on the November–December 2006 issue of MYX Mag, where he praised "Someday" and stressed how well the Soul Siren's versatility and soothing vocals work.
It only shows different scenes of teenage girls crying and reminiscing, while singing to the song and lip syncing Nina's vocals.
The video starts with Nina sitting on a dining table with coffee on it, and singing to the song.
[12] "Someday" was performed on various television appearances, bar gigs, mall tours, and in almost all of Nina's major concerts throughout 2006 to 2010.
She also performed the song, as well as few tracks from the album—including "Love Is Contagious", "I Didn't Mean to Make You Mine", and "Ooh Boy"—in a 2007 episode of MYX Live, hosted by Jett Pangan.
On January 4, 2009, during the introduction of the segment "Sessionistas" on musical variety show ASAP (where she has been part of since 2003), she performed "Someday".
On the August 14, 2010 episode of GMA-7's Comedy Bar, she performed "Someday" while an over-acting superfan was trying to distract her.
She also performed the same song, followed by her 2008 hit single "I Don't Want to Miss a Thing", on the MYX Mo!