from wikipedia : https://en.wikipedia.org/wiki/Open_knowledge
Open knowledge is knowledge that one is free to use, reuse, and redistribute without legal, social or technological restriction. Open knowledge is a set of principles and methodologies related to the production and distribution of how knowledge works in an open manner. Knowledge is interpreted broadly to include data, content and general information.
The concept is related to open source and the Open Knowledge Definition is directly derived from the Open Source Definition. Open knowledge can be seen as being a superset of open data, open content and libre open access with the aim of highlighting the commonalities between these different groups.