As Twitter races to IPO, we take a look back at birdie's biggest moments to date.
Over the past seven years, Twitter has evolved into a medium where anyone with an Internet connection can tune in to see celebrities spar, tragedies unfold, and news break––on both a local and global scale. On the eve of the company's initial public offering on the New York Stock Exchange, which is poised to surpass Google's as the second–largest Internet IPO in history, we took a look at 12 moments that shaped Twitter history.