This document discusses open data concepts and applications. It defines open data as data that can be used, distributed, and shared freely as long as its origin is credited. Open government data aims to increase transparency, citizen engagement, and social/economic value. Examples discussed include open data initiatives in the US and New York City. The document also covers linked open data standards and applications like OpenStreetMap. Crisis mapping examples with OpenStreetMap after the 2010 Haiti earthquake are provided. Potential issues with open data are also mentioned.