Open Data is defined as data that anyone is free to use, reuse, and redistribute subject only to attribution. The document discusses definitions of open data and why transparency and open government initiatives promote opening up public sector data. It provides guidance on how to publish open data by making it available online in open, structured formats and linking it to other open data. Open licenses like Creative Commons are recommended to ensure open data can be freely used and shared. Examples of public agencies that have adopted open data policies are provided.