Mark Jeffrey is a serial entrepreneur and author with Harper Collins. Most recently, Mark founded Guardian Circle and the GUARDIUM Token for global decentralized emergency response (WINNER: CoinAgenda, d10e, LAUNCH Festival; Partner: XPRIZE Foundation). He is also an early pioneer of blockchain technology, having published BITCOIN EXPLAINED SIMPLY (2013) and THE CASE FOR BITCOIN (2016). His previous companies include The Palace (backed by Time Warner, Intel and SoftBank; sold to Communities.com with 10 million users), ZeroDegrees (a business social network sold to InterActiveCorp / IAC in 2004 with 1 million users) and ThisWeekIn (co-founded with Kevin Pollak and Jason Calacanis). He was the founding CTO of Mahalo / Inside.com (backed by Elon Musk, Sequoia, Mark Cuban and others). Mark also worked with Travis Kalanick (CEO Uber) on his first company Red Swoosh.