The term “Open Data” has a very precise meaning. Data or content is open if anyone is free to use, re-use or redistribute it, subject at most to measures that preserve provenance and openness.
There are two dimensions of data openness:
The data must be technically open, which means they must be published in electronic formats that are machine readable and non-proprietary, so that anyone can access and use the data using common, freely available software tools. Data must also be publicly available and accessible on a public server, without password or firewall restrictions. To make Open Data easier to find, most organizations create and manage Open Data catalogs.
Organizations and governments use Open Data licenses to clearly explain the conditions under which their data may be used. Many licenses include both a summary version, intended to convey the most important concepts to all users, and a detailed version that provides the complete legal foundation. Examples include:
Standard licenses can offer several advantages over bespoke licenses, including greater recognition among users, increased interoperability, and greater ease of compliance.
These links provide more information on the definition and licensing of Open Data.
Open Data initiatives can be organized at different levels and often overlap jurisdictions. Country-level initiatives feature data at the national level and below, and are often federated, which means that they aggregate various sources of data at a single location. City and subnational initiatives are similar in design but with a smaller scope. Individual agencies or sectors may have their own data with a specific thematic focus. Other sources may contain specific kinds of data, such as statistical indicators, geospatial data or microdata, such as business and household surveys.