The document discusses fostering big open data through open collaboration. It highlights how cities are growing rapidly and new technologies are unlocking massive streams of data about cities. As these forces collide, every city will become a unique civic laboratory adapting technology to meet local needs. The document outlines New York City's efforts to promote open data through legislation and initiatives like NYC Big Apps, which expose government data sets and encourage developers to build applications using this data. It proposes a system called "Crowdknowing" to enhance open data through techniques like extracting metadata, deriving extra metadata through semantics, statistics, algorithms and crowdsourcing, and performing federated queries across metadata and data.