"Bye bye" is the second single from the album E=MC2. It is cowritten by Mariah, Johnta Austin and Stargate, and produced by Mariah and Stargate. MTV stated that although the song appears to be about her deceased father, Mariah "extends this song about death to be for anybody who just lost somebody". Mariah believed that by making "Bye bye" more open, "everybody could kind of be healed by the song and have their own experience listening to it".

The song premiered on radio April 7, 2008 and has been played on various radio stations in the United States, according to Mediabase. The single became available to download at iTunes on April 14, 2008. Mariah first performed "Bye bye" on T4 4Music and performed it again live on April 14, 2008, the single's digital release date, on The Oprah Winfrey Show and then again, two days later, on American Idol season 7 on April 16. She also performed the song on Good Morning America on April 25, 2008. The single officially went for adds on April 22, 2008 on Mainstream and Rhythm/Crossover stations.

In its review of the song, VH1 said that the song appears to be too basic for an artist like Mariah, and that it was like "insurance - in case nothing else is a hit, here's a sure-shot". In contrast, Rap-Up.com stated that "Bye bye" is "a song everyone can relate to and it will get some listeners teary-eyed.". It also stated that the single would "probably be Mariah's 19th #1". Similarly, Bill Lamb from About.com stated that although "nothing is ever a sure bet to be a #1 hit, Bye Bye is about as close as it gets". He also stated that the song has "universal appeal". Bob Burke from FMQB.com stated that the single was "another gem with multi-format hit potential" and that the single was "destined to be her nineteenth #1 hit". The magazine Blues and Soul gave the single a rating of 8/10, stating that it was "an absolutely stunning track, sung in an absolutely stunning manor by an absolutely stunning diva".

"Bye bye" debuted at #23 on the Billboard Hot 100 as the "Hot Shot Debut", selling 60,000 downloads.

CD-SINGLES

5" CD-single from Australia (3033) no catalogue number promo, picture disc collection Stefano Veneziani Tracklisting: 1. Bye bye (Radio Edit)

5" CD-single from Australia (3059) 1774467 collection Peter Bozoski Tracklisting: 1. Bye bye (Album Version) 2. Touch my body (Subkulcha Radio Edit) 3. We belong together (Jadakiss & Styles P Remix) 4. Bye bye (video)

5" CD-single from Europe (2999) MCBYECDP1 promo collection Gonçalo Peres Tracklisting: 1. Bye bye (Radio Edit) 2. Bye bye (Instrumental)

5" CD-single from Europe / France (3071) MCBYECDP1 promo collection Mike Furhmann Tracklisting: 1. Bye bye (Radio Edit) 2. Bye bye (Instrumental)

5" CD-single from Europe (3067) 602517744653 collection Bernadette Kasander / Marco Hendriks Tracklisting: 1. Bye bye (Album Version) 2. Bye bye (So So Def Remix feat. Jay-Z)

5" CD-single from Europe (3079) 602517744677 collection Wojciech Sichniewicz Tracklisting: 1. Bye bye (Album Version) 2. Touch my body (Subkulcha Radio Edit) 3. We belong together (Jadakiss & Styles P Remix) 4. Bye bye (video) On the insert is a description which says, "for promotional use only - not for sale".

5" CD-single from Thailand (3048) 177 446-7 collection Dave Corneau / Cleyton Bento / Wojciech Sichniewicz Tracklisting: 1. Bye bye (Album Version) 2. Touch my body (Subkulcha Radio Edit) 3. We belong together (Jadakiss And Styles Remix) 4. Bye bye (video) On the back cover, it states the catalogue number as MCBYECDP1 and it says "for promotional use only - not for sale". So it seems to be a promo, but this is probably a mistake.

5" CD-single from the UK (3074) no catalogue number promo collection Andy H Tjondrodihardjo Tracklisting: 1. Bye bye

5" CD-single from the UK (3032) BYECJ1 promo collection Stefano Veneziani Tracklisting: 1. Bye bye (Radio Edit) 2. Bye bye (Instrumental)

5" CD-single from the UK (3043) 1774465 collection Trevor Slatter Tracklisting: 1. Bye bye (Album Version) 2. Bye bye (So So Def Remix feat. Jay-Z)

5" CD-single from the UK (3044) 1774467 collection Trevor Slatter Tracklisting: 1. Bye bye (Album Version) 2. Touch my body (Subkulcha Radio Edit) 3. We belong together (Jadakiss and Styles P Remix) 4. Bye bye (video)

5" CD-single from the UK (3022) no catalogue number promo collection MCEyedol Tracklisting: 1. Bye bye (Radio Edit) 2. Bye bye (Album Version) 3. Bye bye (Instrumental) 4. Bye bye (Acapella) 5. Bye bye (R'n'B Remix feat. Jay-Z - Clean)

5" CD-single from the USA (3030) no catalogue number promo collection Mike Fuhrmann Tracklisting: 1. Bye bye (Radio Edit) 2. Bye bye (Instrumental)

VINYL SINGLES

12" vinyl maxi-single from the UK (3042) 1774468 picture disc collection Gustavo Saczk Tracklisting: 1. Bye bye (Radio Edit) 2: Bye bye (So So Def Remix feat Jay Z)

SHEET MUSIC

sheet music from the USA (3139) HL 00353823 Hal Leonard Corporation piano - vocal - guitar 12 pages collection Raymond Yang