Girl group 4MINUTE is back, and they've already been crowned with the top spot on both the online charts and weekend music programs with their single, "Whatcha Doin' Today?". It's been six years since these girls promised to show us everything they got in just 4 minutes, but they are still fresh and as dominant as ever.

Beginning with their first single "Hot Issue", all their title songs have been big hits. Songs like "Muzik", "HUH", "Mirror Mirror", "Volume Up", and "What's Your Name" were all very popular with the fans. With "Whatcha Doin' Today" also taking the top spots in the music charts, they've proven that they have a long-staying prominence in the K-Pop scene.

While their success is continual, it isn't as though they've repeated the same thing over and over again. So how did they continue their success?

One of the reasons that 4MINUTE can stay successful is that they are good friends outside of the group. They call up each other to hang out even on their off days, and it gives them space to talk about all their problems, including problems within the group. They speak to each other frequently and without reservation, which is probably the secret to their fun performances - they actually have fun with each other on stage.

"Whatcha Doin' Today" is like a sequel to 4MINUTE's previous hit, "What's Your Name". These two songs were written by songwriter Brave Brothers, while their other hits were mostly written by Shinsadong Tiger. The change in the style of songs gave them a chance to refresh their concept and appearance, and they've embraced the opportunity wholeheartedly.

This willingness to radically change their concepts is another reason that 4MINUTE is so successful. "Hot Issue" was fun. "Mirror Mirror" was sexy. "Whatcha Doin' Today" is a mixture of both with a hint of girly charm. The fact that they effectively change concepts so well is one of their greatest strengths.

Some might say that 4MINUTE is a group consisting of HyunA and the four other girls, but the fact is that the other four members have grown to take their own place of prominence in K-Pop. This is also one of the major reasons for their success.

Gayoon is an established model in the fashion industry. Nam Jihyun became a well-loved actress. Kwon Sohyun turned heads by showing her athleticism through archery. Jeon Jiyoon is quickly becoming a skilled rapper. HyunA, of course, is sexy as ever.

4MINUTE may be the prototypical girl group, but all the younger girl groups might do well to follow in their footsteps.