Danger, Inc. was a company specializing in hardware design, software, and services for mobile computing devices. Its most notable product was the T-Mobile Sidekick (also known as Danger Hiptop), which was the first smartphone to capture the attention of pop culture celebrities and teenagers in North America. The Sidekick or Hiptop was a pioneer in client-server ("cloud"-based) smartphones and created the App (Applications) marketplace, later popularized by Android and iOS. Danger was acquired by Microsoft on 11 February 2008, for a price rumored to be around $500 million (USD).