Kara (Hangul: kara, Japanese: kara, often stylized as KARA) was a South Korean pop girl group formed by DSP Media in 2007. The group's final lineup was composed of Park Gyuri, Han Seungyeon, Goo Hara and Heo Youngji. Members Nicole Jung and Kang Ji-young officially departed from the group in 2014, while Kim Sung-hee left in 2008. The group's name comes from the Greek word "chara" (khara, lit. "joy"), which they interpreted to mean "sweet melody".

At the end of January 2009, DSP announced that it would commence voting on January 28 at the group's official website for the follow-up single to "Pretty Girl", which ended on February 2. By the deadline of February 2, "Honey" was the clear winner, with 60% of the votes. The song was remixed from the original version, and also underwent a slight name change from "hani" (Ha-ni) to "Honey". The group released the music video for "Honey" on February 16 and had their first live broadcasting comeback on KBS's Music Bank program on February 13, 2009; a repackaged mini-album entitled Honey followed on February 19 which featured remixed versions of songs from the group's previous EP. "Honey" became the group's first number one single when it topped Gaon's weekly singles chart. The song earned the group their first music show award on M! Countdown on March 5. It held onto the position for three nonconsecutive weeks. The song also won the Mutizen award on SBS's program Inkigayo and the "Best Dance Award" at the 2009 Mnet Asian Music Awards.  At the end of March, the group was chosen for the fourth season of MBC's Idol Show, which marked the group's first hosting duties for a show. The group then had a reality show called MTV Meta Friends, which chronicled a group of fans getting a chance to become friends with the group members. For the show, the group had their first concert since their debut in 2007.  In June 2009, the group stated they would make their comeback in late July, with their concept upgraded. The first teaser pictures of the group were then released in mid-July, showing radical changes in the group's style and also saw a slight return of their "strong and mature" image previously seen from their debut. Their single "Wanna" was released on July 28, 2009 and immediately charted on various digital music charts. The music video was released on July 29, with the full album, Revolution, available online on July 30. Comeback activities commenced on July 31, beginning with KBS's Music Bank; the group performed both "Wanna" and "Mister". "Mister" proved to be popular with netizens due to the "butt dance" that is featured prominently in the choreography. Due to the popularity of "Mister", Kara's overall popularity increased, evidenced by an influx of advertisement requests by various companies; in total, they had more advertisements in October 2009 than they had had the previous two years. "Wanna" also became a number one single for the group and won the Mutizen award on August 30, 2009 from Inkigayo. During promotions for Revolution, the group also performed internationally, including at Bangkok's Parc Paragon.  On November 25, 2009, M.Net premiered the reality show called Kara Bakery, which followed the group as they attempted to plan, open, and advertise their own bakery. The show had 8 episodes and ran until early 2010. All proceeds from the bakery was donated to charity.  On December 14, 2009, it was reported that the group held a fan-meeting for their Japanese fans earlier that year on February marking the group's first promotional tour in Japan. Over 3,000 fans were reportedly registered, exceeding the capacity of the venue which resulted in a second showcase. Answer this question using a quote from the following article:

what was revolution?
full album, Revolution, available online on July 30.