The Open Definition
The Open Definition sets out principles that define “openness” in relation to data and content.
It makes precise the meaning of “open” in the terms “open data” and “open content” and thereby encourages interoperability between different pools of open material.
It can be summed up in the statement that:
“Open means anyone can freely access, use, modify, and share for any purpose (subject, at most, to requirements that preserve provenance and openness).”
Put most succinctly:
“Open data can be freely used, modified, and shared by anyone for any purpose”