Christopher Lloyd graduated with a double-first class degree in history from Cambridge University. Christopher became Technology Editor with The Sunday Times newspaper in London and is now a bestselling author of more than fifteen books on world history including What on Earth Happened? (Bloomsbury), the series of What on Earth Timeline Wallbooks, Absolutely Everything! and more. He is in great demand as a lecturer and public speaker throughout the world, including at TEDx talks, conferences, educational seminars, museums, festivals and schools. Christopher Lloyd lives in Tonbridge, UK.

J. E. Luebering is Executive Editor of Encyclopaedia Britannica and he lives in Chicago, Illinois.

Britannica Group is a global education leader with over 250 years of dedication to seeking out facts and providing insight into the mysteries of the universe. Its beloved Encyclopaedia Britannica is the world's oldest English-language general encyclopedia, first published in 1768 in Edinburgh, Scotland. Today, Britannica continues to create innovative and engaging learning experiences through books, digital content and educational tools. Over three thousand expert contributors have helped make Britannica what it is today, including former U.S. presidents, professional athletes, Nobel laureates, and Pulitzer Prize winners. Britannica's mission to inspire curiosity and the joy of learning helps build the world's future thinkers and innovators. They are based in Chicago, Illinois.