Arianna Huffington co-founded The Huffington Post in 2005 with Kenneth Lerer and Jonah Peretti. The site quickly became popular due to its unique blend of news, blogs, and original content. By leveraging her extensive network and understanding the power of digital media, Arianna was able to attract high-profile contributors and a large audience. The venture was a significant risk, but her commitment to innovation and quality content paid off.