TED Talks Daily (HD video)

What drove David Sengeh to create a more comfortable prosthetic limb? He grew up in Sierra Leone, and too many of the people he loves are missing limbs after the brutal civil war there. When he noticed that people who had prosthetics weren’t actually wearing them, the TED Fellow set out to discover why — and to solve the problem with his team from the MIT Media Lab.

We live in a world of unseeable beauty, so subtle and delicate that it is imperceptible to the human eye. To bring this invisible world to light, filmmaker Louie Schwartzberg bends the boundaries of time and space with high-speed cameras, time lapses and microscopes. At TED2014, he shares highlights from his latest project, a 3D film titled "Mysteries of the Unseen World," which slows down, speeds up, and magnifies the astonishing wonders of nature.

What do rap shows, barbershop banter and Sunday services have in common? As Christopher Emdin says, they all hold the secret magic to enthrall and teach at the same time — and it’s a skill we often don't teach to educators. The science advocate (and cofounder of Science Genius B.A.T.T.L.E.S. with the GZA of the Wu-Tang Clan) offers a vision to make the classroom come alive.

More than 8 million people are crowded together to live in New York City. What makes it possible? In part, it’s the city’s great public spaces — from tiny pocket parks to long waterfront promenades — where people can stroll and play. Amanda Burden helped plan some of the city’s newest public spaces, drawing on her experience as, surprisingly, an animal behaviorist. She shares the unexpected challenges of planning parks people love -- and why it's important.

Seven years ago, Internet activist Aaron Swartz convinced Lawrence Lessig to take up the fight for political reform. A year after Swartz's tragic death, Lessig continues his campaign to free US politics from the stranglehold of corruption. In this fiery, deeply personal talk, he calls for all citizens to engage, and offers a heartfelt reminder to never give up hope.

Do you like curly fries? Have you Liked them on Facebook? Watch this talk to find out the surprising things Facebook (and others) can guess about you from your random Likes and Shares. Computer scientist Jennifer Golbeck explains how this came about, how some applications of the technology are not so cute -- and why she thinks we should return the control of information to its rightful owners.

In 1993, Bill and Melinda Gates took a walk on the beach and made a big decision: to give their Microsoft wealth back to society. In conversation with Chris Anderson, the couple talks about their work at the Bill & Melinda Gates Foundation, as well as their marriage, their children, their failures and the satisfaction of giving most of their money away.

On March 17, 2014, a group of physicists announced a thrilling discovery: the “smoking gun” data for the idea of an inflationary universe, a clue to the Big Bang. For non-physicists, what does it mean? TED asked Allan Adams to briefly explain the results, in this improvised talk illustrated by Randall Munroe of xkcd.

Do you have a TED Talk inside, just bursting to come out? Take this tongue-in-cheek musical journey to “Give Your Talk.” A musical love letter to our speakers -- written, directed and performed by the TED staff.

When fashion model Geena Rocero first saw a photo of herself in a bikini, "I thought ... you have arrived!" As she reveals, that’s because she was born with the gender assignment “boy.” In this moving talk, Rocero tells the story of becoming who she always knew she was.

Hugh Herr is building the next generation of bionic limbs, robotic prosthetics inspired by nature's own designs. Herr lost both legs in a climbing accident 30 years ago; now, as the head of the MIT Media Lab’s Biomechatronics group, he shows his incredible technology in a talk that's both technical and deeply personal — with the help of ballroom dancer Adrianne Haslet-Davis, who lost her left leg in the 2013 Boston Marathon bombing, and performs again for the first time on the TED stage.

When hundreds of thousands of tweets are fired every second, a one-in-a-million chance -- including unlikely-sounding scenarios that could harm users -- happens about 500 times a day. For Del Harvey, who heads Twitter’s Trust and Safety Team, these odds aren’t good. The security maven spends her days thinking about how to prevent worst-case scenarios while giving voice to people around the globe. With deadpan humor, she offers a window into how she keeps 240 million users safe.

We humans set a premium on our own free will and independence ... and yet there's a shadowy influence we might not be considering. As science writer Ed Yong explains in this fascinating, hilarious and disturbing talk, parasites have perfected the art of manipulation to an incredible degree. So are they influencing us? It's more than likely.

When Bran Ferren was just 9, his parents took him to see the Pantheon in Rome — and it changed everything. In that moment, he began to understand how the tools of science and engineering become more powerful when combined with art, with design and beauty. Ever since, he's been searching for a convincing modern-day equivalent to Rome's masterpiece. Stay tuned to the end of the talk for his unexpected suggestion.

Pakistani educator Ziauddin Yousafzai reminds the world of a simple truth that many don’t want to hear: Women and men deserve equal opportunities for education, autonomy, an independent identity. He tells stories from his own life and the life of his daughter, Malala, who was shot by the Taliban in 2012 simply for daring to go to school. "Why is my daughter so strong?” Yousafzai asks. “Because I didn’t clip her wings."