Created as a resource, the BMW Guggenheim Lab 100 Urban Trends offers a glossary of contextualized definitions that apply to the way we understand, design, and live in cities. Integral to this glossary is the concept of cities as “idea makers.” In cities, people come together, share their thoughts and common interests, and generate the ideas that shape our world. Dense, growing cities have been and continue to be the catalyst for human progress, powered by daily proximity among their citizens as much as anything else. Despite some of the drawbacks of such massive urban centers, they may well embody the future for human life. Today’s cities are competing to attract more people; greater urban density can mean more conflict, but it can also produce a greater diversity of viewpoints and more opportunity for positive change.