f(x)

f(x) is a South Korean girl group formed by SM Entertainment, centered on Victoria, Amber, Luna, and Krystal, with Sulli part of the group's earlier history. They debuted in 2009 with "LA chA TA."

The group became one of K-pop's clearest examples of a musically experimental idol act. f(x) often worked with electronic pop, synth textures, unusual song structures, and fashion-forward styling, creating a reputation that was cooler and more art-pop leaning than many girl groups of the same era.

Albums such as Pink Tape and 4 Walls helped cement that reputation, especially among fans who valued cohesive concepts and less predictable production. The group's image also benefited from the members' distinct public roles: Victoria's performance and variety presence, Amber's androgynous image, Luna's vocals, Krystal's cool visual identity, and Sulli's early prominence.

The fandom is known as MeU. f(x) has not followed a normal active-group path in recent years, but their influence remains strong because they showed how experimental production and idol-pop accessibility could sit together.