"Girlfriend" is a song by Canadian pop-punk singer Avril Lavigne, released as the lead single from her third studio album, The Best Damn Thing. It was produced by Lukasz Gottwald. "Girlfriend" became Lavigne's biggest hit in the United States, where it became her first number one single in the U.S. Hot 100. It topped the chart in Australia for 6 weeks, and reached number two in the United Kingdom. A remix featuring rapper Lil Mama was released in June 2007. The song was recently named by Billboard Magazinethe #94 Top Single of the decade. It was also the top selling song in 2007 with sales of over 7.3 million from 72 different countries.

The song involves Lavigne proclaiming a crush on a boy who currently has a girlfriend already, and features the typical 80's pop-punk influence and power pop of her earlier songs. Lavigne said on the DVD side of the deluxe edition of The Best Damn Thingthat in the bridge when the listener hears hand clapping, the accompanying giggling was created by Lavigne and Gottwald, despite it sounding like a girl. "Girlfriend" is in the video game Burnout Dominatorin English, Japanese, Spanish, and Chinese. It also appears in Burnout Paradisebut this time only in English. This song is recorded in 7 languages other than English. It is the theme song of Japanese talk show Cartoon KAT-TUN- on which Lavigne appeared on May 2, 2007 - as well as being the insert song for popular Japanese manga based drama Hanazakari no Kimitachi e. It is featured in the theatrical trailer for the 2007 live-action Bratzfilm, and in a trailer for the film I Now Pronounce You Chuck and Larry, and also for Bring It On: In It to Win It. Lavigne performed the song on The Tonight Show with Jay Lenoon June 15, 2007.

The song was #35 on Rolling Stone's list of the 100 Best Songs of 2007. This song was also #77 on MTV Asia's list of Top 100 Hits of 2007. Also was listed as the number 1 hit of 2007 according to MTV Latin America. . Note, Girlfriend peaked as number one in the North/Central Latin American Version of "Los 100 Más Pedidos 2007" (The 100 Top Hits of 2007), while in the South Latin American Version of "Los 100 Más Pedidos 2007" it peaked at number 3, losing the first place to "With Love" by Hilary Duff. "Girlfriend" also won the Best Song of the Year at the 2008 Kids' Choice Awards. It beat "Big Girls Don't Cry", "Don't Matter", and "Beautiful Girls".

Critics have compared the middle section of the song with the bridge from Toni Basil's "Mickey".

Reviewers have noted that the chorus bears a resemblance to The Rubinoos' 1979 single "I Wanna Be Your Boyfriend", in which they sing "Hey hey, you you, I wanna be your boyfriend" similar to "Hey hey, you you, I could be your girlfriend" in "Girlfriend". The song can be heard on the Rubinoos' MySpace page.

On May 25, 2007, Lavigne, her songwriter Lukasz Gottwald, her record label, and Apple Inc. were sued by James Gangwer and Tommy Dunbar, songwriters for The Rubinoos, over claims that "Girlfriend" infringes their copyright on their 1979 song "I Wanna Be Your Boyfriend". Lavigne's manager, Terry McBride, denied that "Girlfriend" was copied from "I Wanna Be Your Boyfriend", and pointed out that "Boyfriend" itself is similar to The Rolling Stones' "Get off of My Cloud". McBride said he hired a musicologist to compare the songs; according to McBride the musicologist reported that the songs were totally dissimilar, even a different meter. Prominent music critics such as Stephen Thomas Erlewine of Allmusichave publicly noted that the song is a "total lift from the Rubinoos' song". McBride said that Lavigne has no current plans to settle the case, but will consider the costs of defending the case against those of settling. In January 2008, the lawsuit was settled and Gangwer and Dunbar released a statement saying that the similarities between the songs were based on "certain common and widely used lyrics" and that they "completely exonerate Avril and Luke from any wrongdoing of any kind in connection with the claims made by us in our lawsuit."

The world premiere of the music video was announced to be on MTV's Total Request Liveand MuchMusic's MuchOnDemandon February 26. However, it premiered in New Zealand on Music Station C4 on February 20. It was in heavy rotation on European music TV channel VIVA Polska on February 23 as well.

The music video was directed by The Malloys and filmed at Golf 'n' Stuff in Norwalk, California. It features two girls: one with an innocent persona, glasses and red hair (Lavigne), and one with a rebellious persona and black hair (also Lavigne). The video begins inside the building where the red-haired girl and her boyfriend are walking together. Lavigne sees her and shows her an intimidating disposition. As the couple walk away, Lavigne begins to sing the song and tries her luck on the red-haired girl's boyfriend. Featured in the video are scenes of Lavigne fighting over the man with the red-haired girl and trying to outdo her repeatedly. Between the scenes show Lavigne singing with her band accompanying her at the back. The video also featured Lavigne and her friends dancing within the comfort room (restroom) background. After the starting scene, the video shows them at Li'l Indy, where they ride go-carts. Here, Lavigne is seen viciously bumping the car of the red-haired girl, causing her to spin around and lose control. Next, the red-haired girl and her boyfriend get inside a photo booth where Lavigne hears them and grabs the red-haired girl away before they take pictures. Lavigne's friends then block the red-haired girl's way to give her more time.

The next scene shows the couple eating together, where Lavigne sees them, throws the food away and kisses the red-haired girl's boyfriend. It is nighttime when the next scene was shown. This scene takes place in a miniature golf course where the couple are playing, and the red-haired girl cheerfully wins.

Unfortunately for her, Lavigne and her friends are also present at the scene. As soon as she and her friends see them, Lavigne hits her in the head with a golf ball, and the red-haired girl splashes down below and into the water. Her boyfriend tries to grab her hand but misses. Finally, the last scene shows Lavigne waiting for the man. As he comes toward her, they soon hold hands together, and the red-haired girl sees them and tries to seize Lavigne (at the same time trying to get her boyfriend back). But Lavigne ducks down and the man moves sideways as soon as the red-haired girl charges towards Lavigne. She then tumbles all the way down and falls into a Porta Potty ahead, where she gives a look of desperation towards the camera, showing that she has failed to win back her boyfriend. Lavigne then finally wins the youth's affections. The video ends when she takes her new boyfriend into a bathroom stall and slightly opens the door after a moment and gives a thumbs up. Lavigne's boyfriend in the video is played by American model Bryan McMullin and dresses similarly to the "rocker" Lavigne in the video. The video features Lavigne's previous guitarist Evan Taubenfeld, and Lavigne's brother Matt on bass.

Lil Mama and Lavigne shot a video for the remix of "Girlfriend", which was directed by R. Malcolm Jones.

The first 15 seconds of the video include an audio sampling of "Arcade Ambiance 1983".

On July 18, 2008 "Girlfriend" became the most viewed video of all time on YouTube and in August of that year, surpassed 100 million views, the first YouTube video to reach that milestone, overtaking "Evolution of Dance" by Judson Laipply. The YouTube video of the song was accused of having an exaggerated number of views due to the use of a web link posted by AvrilBandAids, a fansite devoted to Avril Lavigne. Clicking on the link would automatically reload the YouTube video of Girlfriend every fifteen seconds. Fans of Avril Lavigne were encouraged to: "Keep this page open while you browse the internet, study for exams, or even sleep. For extra viewing power, open up two or more browser windows at this page!" It is expected that Avril's YouTube video views have earned in excess of $2 million (U.S). In November 2009, RCA Records removed the video of the song from YouTube, by which time it had received around 130 million views. The official video is now hosted on Vevo, a premium music video site owned by Google and Sony.

"Girlfriend" was premiered on Edmonton radio station 91.7 The Bounce before the official date it was supposed to be aired; the two DJs who played it were taken off the air shortly after. The single appeared and was available for download on the U.S. iTunes Store on February 23, but was subsequently removed the following day. It was made available again on February 27.

Because of digital download sales in excess of 122,000, the song debuted at number five on the U.S. Hot 100 chart, the highest debut of her career. Afterwards it became Lavigne's first song to reach number one on the Hot 100, in the issue dated May 5, 2007; her previous highest peak on the chart was with 2002's "Complicated", which reached number two. It remained in the top ten for eighteen weeks, and has since been downloaded over 3 million times.

"Girlfriend" debuted on the Australian ARIA Singles Chart at number three. The following week it reached number-one, and it remained at the top for six non-consecutive weeks, equaling Lavigne's previous number-one single on the ARIA Charts, "Complicated". After three weeks on the charts, it was certified gold by ARIA, then platinum after seven weeks for sales in excess of 70,000 copies. It was then certified double platinum, sales in excess of 140,000. In 2008, it was certified quadruple platinum for sales of 280,000.

On the UK Singles Chart, "Girlfriend" peaked at number two, surpassing "Complicated" as Lavigne's highest peaking single on the chart. The song ended 2007 as the years 20th biggest-selling single in the UK and spent 27 weeks inside the chart and is Lavigne's biggest hit in the UK to date.

It won the Award for "Canción del Año" (Song Of The Year) in "Los Premios MTV Latinoamérica 2007" (The Latin American MTV Awards) and was nominated for "Monster Single" in the MTV Video Music Awards 2007. It won Most Addictive Track (Single Of The Year) at the MTV Europe Music Awards

There is a live video version of the song, which was part of The Best Damn Tour - Live in Toronto, and was sent to Brazil Music Channels (such as MTV and Multi Show) and was released to promote the DVD release for The Best Damn Tour 2008.

Seven additional versions of the song are available to enhance its worldwide marketability with the chorus sung in French, German, Italian, Japanese, Mandarin, Portuguese and Spanish language. The other parts of the song are in English. According to Lavigne's label, a Hindi version was attempted but Lavigne found it too difficult to record because the correctly pronounced lyrics did not best match the meter of the song.

There is also an edited version for radio, because of explicit lyrics. There are two official censored versions: one blanking the word "motherfucking" in the line "I'm the motherfucking princess" and the other replacing it with "I'm the one and only princess". It is played on Canadian and Malaysian radio stations, and on Z100 in New York City. However, on other radio stations the entire word is cut out or just the word "mother", as in the version on the clean edition of the album, is said.

The official remix was leaked onto the Internet in May 2007 and features rap verses from American hip-hop musician Lil Mama. Lavigne sings the chorus and bridge and Lil Mama's rap verses are substituted for the original verses.

(4988017647615; Released March 21, 2007)

A code included on the CD to download the ringtone online.

In September 2009, punk rock American band Zebrahead released "Girlfriend" as the first single of their new album Panty Raid, which was released on November 4, 2009, in Japan and December 8 in the rest of the world. The album is noticed to only have cover versions of women's famous pop songs of the past two decades. It runs 3:05 and is fast-paced, thanks to Ali rap sing style. It was peaked in the Hot Modern Rock Tracks in the first week in the #84 place.

The music video of the song was released in mid October and is a parody of the original "Girlfriend" video, with Ali playing the "Bad Avril" and Matty playing the good one. It resembles numerous situations that occur in the original video, but with a more comic sense into the video.

"Girlfriend" was released in a number of countries over a three-month period. The remix featuring Lil Mama was released on June 15 in Taiwan, and on July 25 in the United States.

Reaching number-one on numerous music charts worldwide, "Girlfriend" is Lavigne's most successful charting single.