Open Education Week (OE Week) is an annual celebration and opportunity to actively share and learn about the latest achievements in Open Education worldwide!
Open Education is about strengthening education by creating open resources. Open Educational Resources (OER) are teaching, learning, and research materials that are either (a) in the public domain or (b) licensed in a manner that provides everyone with free and perpetual permission to engage in the 5R activities.

An open license permits users of a resource to participate in the 5R activities of OER:

Retain: Make, own, and control your own copy of the content
Reuse: Use the content as-is
Revise: Adapt, adjust, modify, improve, or alter the content
Remix: Combine the original or revised content with other OER to create something new
Redistribute: Share your copies of the original content, revisions or remixes with others