about T-ARA

T-ara  is a South Korean girl group formed by Core Contents Media in 2009. Before their debut, there was a high level of interest in the group as they were called "Super Rookies" and had been training for three years prior to debut.Originally a five-member group, they released their first song "Good Person" for the soundtrack of the Korean drama Cinderella Man in April 2009. In June 2009 members Jiwon and Jiae left the group, delaying the group's debut. The next month, T-ara regrouped to become a six-member group with the addition of Boram, Qri, and Soyeon, and released their debut single "거짓말" ("Lies"). In July 2010, T-ara introduced a new member, Ryu Hwayoung, to become a seven-member group. T-ara uses a rotating leader system, and has a different member of the group elected as leader each year, in order to give both the group and the individual members the opportunity to grow in a new direction.

about 2NE1

2NE1 is a South Korean hiphop/pop girl group formed by YG Entertainment in 2009. 2NE1 consists of four members: Bom, Dara, CL and Minzy. The group's name 2NE1 stands for "New Evolution of the 21st Century".
They first appeared in "Lollipop" in commercial campaign with Big Bang for LG Electronics, and their debut single "Fire" was released on May 6, 2009. Since then, the group has released two extended plays,  2NE1 and 2NE1 Second Mini Album, and one studio album, To Anyone. 
Fans of 2NE1 call themselves "Blackjacks", a reference to the card game Blackjack.

about f(x)

f(x) is a five member South Korean girl group formed by SM Entertainment in 2009. The name is a play on the mathematical notation for function, and when input with different 'x', there can be many different outcomes. f(x) strives to be the kind of girl group that can change and adapt to many situations. The group members have also been nicknamed "function girls". The group made their debut on September 1, 2009 with release of a digital single "La Cha Ta" (stylized as "LA chA TA"). The quintet consists of Victoria, Amber, Luna, Sulii and Krystal.

about Kara

Kara is a South Korean girl group signed with DSP Media (DSP). The band name Kara comes from the Greek Word "chara", which the group mean "sweet melody". Kara started as a four-member group and debuted with a "strong female" image through R&B tyle for their first album "The First Blooming" n 2007. In 2008, Kim Sunghee departed the group due to parental pressure, and two new members were brought in; as such, the group currently consists of five members: Park Gyuri, Han Seung-yeon, Nicole Jung, Goo Hara, and Kang Jiyoung. The addition of the two new members also faced a change in the group's original image to a "pretty but natural" appeal. The five-member band went on to achieve their first number one song with "Honey".