The author of "Investing in Kids," Timothy Bartik studies state and local economies -- and analyzes the benefits of preschool as an economic development program.

Writer, comic and mental health activist Kevin Breel speaks up about depression.

Sebastián Bortnik's work is focused on preventing cyber attacks.

Ken Jennings holds the record for most consecutive wins on the classic American trivia game show, Jeopardy.

Mac Barnett is a bestselling author of books for children.

Agnes Larsson brings happiness and inspiration to millions of Minecraft players as they explore the open-ended creation game, block by block.

With her viral talk from TED2012 and her mega-bestseller "Quiet," Susan Cain urged society to cultivate space for the undervalued, indispensable introverts among us. Now, with her new bestseller "Bittersweet," she's back to explore the surprising lessons sorrow and longing teach us about creativity, connection and love.

TED Fellow Karen "Kaz" Lucas is a leader in the world of arts and culture in Kenya.

TED Fellow Brandon Clifford mines knowledge from the past to design new futures.

Clay Shirky argues that the history of the modern world could be rendered as the history of ways of arguing, where changes in media change what sort of arguments are possible -- with deep social and political implications.

A practicing surgeon for three decades, Sherwin Nuland witnessed life and death in every variety. Then he turned to writing, exploring what there is to people beyond just anatomy.

First Lady Michelle Obama, a lawyer and administrator, is an advocate for working parents and education for girls all around the world.

Carlo Ratti directs the MIT SENSEable City Lab, which explores the "real-time city" by studying the way sensors and electronics relate to the built environment.

Mia Birdsong advocates for strong communities and the self-determination of everyday people.

Jonathan Klein runs Getty Images, a stock photo agency whose vast archive of still photography and illustrations is a mainstay of the creative class.

Julie Lythcott-Haims speaks and writes on the phenomenon of helicopter parenting and the dangers of a checklisted childhood -- the subject of her book, "How to Raise an Adult."

2005 TED Prize winner Edward Burtynsky has made it his life's work to document humanity's impact on the planet. His riveting photographs, as beautiful as they are horrifying, capture views of the Earth altered by mankind.

Deb Roy studies how children learn language, and designs machines that learn to communicate in human-like ways. On sabbatical from MIT Media Lab, he's working with the AI company Bluefin Labs.

With astronaut eyes and ethnographer curiosity, Tricia Wang helps corporations grow by discovering the unknown about their customers.

Cave art researcher