The sum of what is known about specific domain: the body of truth, information, and principles acquired by domain experts.

Adapted from: http://www.merriam-webster.com/dictionary/knowledge [-]

expresses concepts and provides applications of the underlying data and information models

Rowley, J. (2007). The wisdom hierarchy: representations of the DIKW hierarchy. Journal of information science, 33(2), 163-180. https://doi.org/10.1177/0165551506070706 [Sage Journal]

Knowledge is know-how, and is what makes possible the transformation of information into instructions. Knowledge can be obtained either by transmission from another who has it, by instruction, or by extracting it from experience.

R.L. Ackoff, From data to wisdom, Journal of Applied Systems Analysis 16 (1989) 3–9. [CITATION]