What is "open-data"

Open data is the idea that some data must be freely available so that everyone can use and republish as they wish, without copyright restrictions, patents or other control mechanisms.

Some restrictions on the reuse or disclosure of data, such as citation of the author, are allowed within the concept of open license. The concept is detailed in http://opendefinition.org

Public domain data is the most open form, however they will not always explicitly present a license. This is an implicit understanding of the country’s legislation. In Brazil, for example, the data tables fixed in the text of Law are automatically transferred to the public domain.