"Someday (I Will Understand)" is a song recorded by American singer Britney Spears. It was written by Spears and produced by Guy Sigsworth. The song was released on August 18, 2005, by Jive Records, as the sole single from Spears' first extended play, Britney & Kevin: Chaotic (2005). In July 2004, Spears announced her engagement to American dancer Kevin Federline, later revealing she would be taking another career break to start a family. Spears wrote the song two weeks before knowing she was pregnant with her first child, Sean Preston Federline. A pop ballad, "Someday (I Will Understand)" lyrics refer to a feeling of empowerment as a pregnant woman. A remixed version of the song was included on the 2005 remix compilation, B in the Mix: The Remixes.
"Someday (I Will Understand)" has received mixed reviews from music critics. A few reviewers considered it as a lesson on the singer's history and a "tear-jerker" ballad, while others considered it a non-savable "flop single". The song reached the top ten in Denmark, Sweden and Switzerland and also charted in a number of European countries. An accompanying music video, directed by Michael Haussman, premiered on the finale of Britney & Kevin: Chaotic. Entirely shot in black-and-white, the music video features Spears as a pregnant woman and portrays a transformation of her character.
In July 2004, Spears announced her engagement to American dancer Kevin Federline, whom she had met three months before. The romance received intense attention from the media, since Federline had recently broken up with actress Shar Jackson, who was still pregnant with their second child at the time. The initial stages of their relationship were chronicled in Spears's first reality show Britney & Kevin: Chaotic. They held a wedding ceremony on September 18, 2004, but were not legally married until three weeks later on October 6 due to a delay finalizing the couple's prenuptial agreement. In October 2004, the singer announced she would be taking another career break to start a family. Spears gave birth to her first child, Sean Preston Federline, on September 14, 2005.
"Someday (I Will Understand)" was composed by Spears on the piano at her house, two weeks before she learned of her pregnancy with Sean Preston. She explained the song came "like a prophecy... when you're pregnant, you're empowered". It was produced by Guy Sigsworth, who previously worked with the singer on "Everytime" (2003). Spears recorded her vocals for the song at Conway Studios in Los Angeles, California, and at Frou Frou Central in London. The piano was played by Spears herself, while all other instruments and mixing were done by Sigsworth. Background vocals for the song were provided by Kate Havnevik.
"Someday (I Will Understand)" received mixed reviews from music critics. While reviewing Britney & Kevin: Chaotic, Mike McGuirk of Rhapsody noted, "Britney now sings about either the husband or the kid. (Sorry, people. It's a sad day for the middle-aged American male sicko.) For everyone else, these bonus tracks further Spears' upward path of totally bangin' production and almost uncanny Prince-channeling." Gil Kaufman of MTV thought the song a "horrible Britney ballad with the black-and-white video that began her descent into madness." Leo Ebersole of Chicago Tribune considered it "a fictional piece", while another reviewer from the same newspaper noted that "as a matter of fact, the song is more or less a lesson in Britney history." Becky Bain of Idolator praised the track, stating that "Britney goes genuine for this ode to her unborn baby." Kurt Kirton of About.com said that "And Then We Kiss" and other remixes of songs like "Toxic" and "Someday (I Will Understand)" on the remix album B in the Mix: The Remixes "hold their own". IGN writer Spence D. noted the Hi-Bias Signature Radio Remix "reverberates with all the clichés that often stifle the music that rustles through the late night/early morning club scenes around the world." Rolling Stone contributor Barry Walters gave the song's remix a negative review, saying that "nothing can rescue Spears' freakishly sappy flop single "Someday (I Will Understand)"." Bradley Stern also of MTV, however, praised the Leama & Moor Remix, saying it "transforms the tearjerker of a ballad into a full-on trance anthem. Big beats, stuttering vocals -- it's heartbreak on the dance floor."
On September 1, 2005, "Someday (I Will Understand)" debuted at number 46 on the Swedish Singles Chart. It peaked at number 10 the following week. In Switzerland, the song debuted at number eight on the week of September 4, 2005. On September 9, 2005, the song debuted in the Danish Singles Chart at number 11. The following week, it peaked at the eight position. "Someday (I Will Understand)" also reached the top 20 in Belgium (Flanders and Wallonia), Finland and Norway and charted in Austria and the Netherlands. "Someday (I Will Understand)" has sold 60,000 paid digital downloads in the United States, according to Nielsen SoundScan.
The music video for "Someday (I Will Understand)" was directed by Michael Haussman. Spears commented that he "[did] a great job capturing the song, the essence and the emotion" and added that the video had "a different feeling" from any of her previous videos. It was shot entirely in black-and-white. Spears asserted that her life had "come full circle" and implied that in the process she underwent changes in her soul and body, as shown in the video. It premiered on June 14, 2005 during the fifth and last episode of Spears's reality show Britney & Kevin: Chaotic, titled "Veil of Secrecy". The music video features a pregnant Spears lying in bed and walking around a house while singing to her unborn child. She also gazes through the window at the Roman sculptures in the garden.
Hayley Butler of Jam! said "the video is a far cry from the snake handling, sweating and skimpy Britney videos of the past. Dressed in a classy silk dress, she runs through gardens, lies in bed and walks through the grass, all with a burgeoning belly." John Mitchel of MTV included the video on the list "Beyonce, Britney And Madonna: What To Expect When You're Expecting — Music Video Edition" in 2011. Despite praising the track, Idolator blogger Becky Bain stated that "at this point she still looks like a teenager herself, so it's a little disconcerting seeing her with that huge belly, singing about motherhood."