1. Gwen Stefani, "Hollaback Girl"
The song was the third single released from Stefani's debut solo album, Love. Angel. Music. Baby. and was reportedly written as a response to Courtney Love calling her a "cheerleader" in Seventeen magazine — one of Love's several disses toward her in their long-standing feud. The infectious single peaked at No. 1 on the Billboard Hot 100, so game, set, and match.
Where you probably heard it most: EVERYWHERE! 'Cause that shit was bananas — B-A-N-A-N-A-S. And now I'm sure you'll have the song stuck in your head for the rest of the day.
2. Rihanna, "Pon de Replay"
"Pon de Replay" was Rihanna's debut single from her first album, Music of the Sun. The song peaked at No. 2 on the Billboard Hot 100; Mariah Carey's "We Belong Together" held it from nabbing the top spot.
Where you probably heard it most: At the club (if you were old enough) and/or on repeat on your iPod.
3. Missy Elliott, "Lose Control"
The first single off Missy's sixth album, The Cookbook, peaked at No. 3 on the Billboard Hot 100. The accompanying music video went on to win two MTV VMAs (Best Dance Video and Best Hip-Hop Video) and a Grammy Award for Best Music Video.
Where you probably heard it most: Besides the club, MTV, VH1, and BET, which played the video on heavy rotation.
4. Kanye West, "Gold Digger"
"Gold Digger" was the second single released from West's second album, Late Registration. The song was actually never meant for West; he originally produced the song for rapper Shawnna's debut album, but she passed on it. Her loss was his gain: The song hit No. 1 on the Billboard Hot 100.
Where you probably heard it most: With that one friend (or maybe it was you) who played the song on repeat in the car and would sing along to the Jamie Foxx verses.
5. Pussycat Dolls, "Don't Cha"
The lead single released from the Pussycat Dolls' debut album, PCD, peaked at No. 2 on the Billboard Hot 100. The song was co-written by Cee Lo Green, Sir Mix-a-Lot, and Busta Rhymes (who also appeared on the track).
Where you probably heard it most: Being sung by your little sister or cousin who had no idea what the lyrics were about.
6. 50 Cent, "Just a Lil Bit"
The third single released from 50's second album, The Massacre, peaked at No. 3 on the Billboard Hot 100.
Where you probably heard it most: The mix CD/iTunes playlist you made to get you in a party mood.
7. Gorillaz, "Feel Good Inc."
Where you heard it most: On every alt-rock and top 40 radio station.
8. The Killers, "Mr. Brightside"
"Mr. Brightside" was the second song released from The Killers' debut album, Hot Fuss. Originally released in late 2004, the song enjoyed a long run on the charts before peaking at No. 10 on the Billboard Hot 100 in early June.
Where you probably heard it most: Every karaoke bar across the country.
9. Bow Wow, "Let Me Hold You"
The first single released off Bow Wow's fourth album, Wanted, peaked at No. 4 on the Billboard Hot 100.
Where you probably heard it most: Playing in the background at a house party or pool party.
10. Weezer, "Beverly Hills"
The first single off Weezer's fifth album, Make Believe, peaked at No. 13 on the Billboard Hot 100 and remains their highest-ranking single to date.
Where you probably heard it most: While shopping at the mall, in your car, watching MTV...basically you really couldn't escape this song.
11. Lifehouse, "You and Me"
The first single off the band's third album, Lifehouse, peaked at No. 5 on the Billboard Hot 100. The song also surpassed their previous big hit "Hanging by a Moment" to become their biggest chart-topper ever.
Where you probably heard it most: On the mix CD you made about you and your S.O.
12. The Black Eyed Peas, "Don't Phunk With My Heart"
"Don't Phunk With My Heart" was the first single off the band's fourth album, and second with Fergie, Monkey Business. The song peaked at No. 3 on the Billboard Hot 100 and also went on to win a Grammy for Best Rap Performance by a Duo or Group.
Where you probably heard it most: On your played-out copy of Monkey Business that you downloaded from LimeWire.
13. Amerie, "1 Thing"
The song was originally released in February 2005 as a single off the Hitch soundtrack; the song was also included on Amerie's second studio album, Touch, which came out later that year. After months on the charts, the song finally peaked at No. 8 on the Billboard Hot 100 in June.
Where you probably heard it most: At every club, wedding, quinceañera, bar/bat mitzvah, house party, backyard barbecue, etc.
14. Kelly Clarkson, "Behind These Hazel Eyes"
The song was the second single released from Clarkson's second album, Breakaway, and it followed her MEGA hit "Since U Been Gone." The song peaked at No. 6 on the Billboard Hot 100.
Where you probably heard it most: Well, if you broke up with someone around this time, this was probably your anthem that you played on repeat.
15. Mariah Carey, "We Belong Together"
Without a doubt, "We Belong Together" — which was the second single released from her album The Emancipation of Mimi — was the biggest song of the summer: It spent an impressive 14 weeks at No. 1 on the Billboard Hot 100. In fact, the song was the biggest song of 2005. As well as one of the biggest songs of the decade.
Where you probably heard it most: Um, EVERYWHERE. Let's face it, this song was so big you probably sang it in your sleep. Heck, you're probably singing it now!