Conversation so far:
What happened regarding South Korean group Kara in 2009?
At the end of January 2009, DSP announced that it would commence voting on January 28 at South Korean group Kara's official website.
What did the DSP vote on regarding South Korean group Kara at the end of January 2009?
The vote was for the follow-up single to Pretty Girl, which ended on February 2.
Was the South Korean group Kara single Pretty Girl successful?
The teaser video and music video for South Korean group Kara single Pretty Girl were well received by the public.

Question: what was revolution?
Self-contained rewrite: What was revolution by Kara?