At 16, Rana Abdelhamid started teaching self-defense to women and girls in her neighborhood. Almost 10 years later, these community classes have grown into Malikah: a global grassroots network creating safety, power and solidarity for all women. How did she do it? Abdelhamid shares three ingredients for building a movement from the ground up.

Kakenya Ntaiya turned her dream of getting an education into a movement to empower vulnerable girls and bring an end to harmful traditional practices in Kenya. Meet two students at the Kakenya Center for Excellence, a school where girls can live and study safely -- and uplift their community along the way. "When you empower a girl, you transform a community," Ntaiya says.

Robot brains are getting smarter and smarter, but their bodies are often still clunky and unwieldy. Mechanical engineer Christoph Keplinger is designing a new generation of soft, agile robot inspired by a masterpiece of evolution: biological muscle. See these "artificial muscles" expand and contract like the real thing and reach superhuman speeds -- and learn how they could power prosthetics that are stronger and more efficient than human limbs.

In an unmissable talk, journalist Carole Cadwalladr digs into one of the most perplexing events in recent times: the UK's super-close 2016 vote to leave the European Union. Tracking the result to a barrage of misleading Facebook ads targeted at vulnerable Brexit swing voters -- and linking the same players and tactics to the 2016 US presidential election -- Cadwalladr calls out the "gods of Silicon Valley" for being on the wrong side of history and asks: Are free and fair elections a thing of the past?

Can Twitter be saved? In a wide-ranging conversation with TED's Chris Anderson and Whitney Pennington Rodgers, Twitter CEO Jack Dorsey discusses the future of the platform -- acknowledging problems with harassment and moderation and proposing some fundamental changes that he hopes will encourage healthy, respectful conversations. "Are we actually delivering something that people value every single day?" Dorsey asks.

At the center of a galaxy more than 55 million light-years away, there's a supermassive black hole with the mass of several billion suns. And now, for the first time ever, we can see it. Astrophysicist Sheperd Doeleman, head of the Event Horizon Telescope collaboration, speaks with TED's Chris Anderson about the iconic, first-ever image of a black hole -- and the epic, worldwide effort involved in capturing it.

In the early 1990s, a scandal rocked evolutionary biology: scientists discovered that songbirds -- once thought to be strictly monogamous -- engaged in what's politely called "extra-pair copulation." In this unforgettable biology lesson on animal infidelity, TED Fellow Danielle N. Lee shows how she uses hip-hop to teach science, leading the crowd in an updated version of Naughty by Nature's hit "O.P.P."

How often do you think about the air you're breathing? Probably not enough, says entrepreneur and TED Fellow Romain Lacombe. He introduces Flow: a personal air-quality tracker that fits in your hand and monitors pollution levels in real time. See how this device could help you track and understand pollution street by street, hour by hour -- and empower you to take action to improve your health.

In a story of scientific discovery, chemical biologist David R. Liu shares a breakthrough: his lab's development of base editors that can rewrite DNA. This crucial step in genome editing takes the promise of CRISPR to the next level: if CRISPR proteins are molecular scissors, programmed to cut specific DNA sequences, then base editors are pencils, capable of directly rewriting one DNA letter into another. Learn more about how these molecular machines work -- and their potential to treat or even cure genetic diseases.

The Silent Generation, baby boomers, Generation X, millennials, Gen Z -- we're all in the workforce together. How are our assumptions about each other holding us back from working and communicating better? Social psychologist Leah Georges shows how we're more similar than different and offers helpful tactics for navigating the multigenerational workplace.