Tacit knowledge (as opposed to formal, codified or explicit knowledge) is the kind of knowledge that is difficult to transfer to another person by means of writing it down or verbalizing it. For example, stating to someone that London is in the United Kingdom is a piece of explicit knowledge that can be written down, transmitted, and understood by a recipient.

Tacit knowledge
Tacit knowledge
Implicit learning of tacit knowledge
The Role of Tacit Knowledge in Group Innovation1
Implicit learning and tacit knowledge.
Chapter 11–The Role of Tacit Knowledge in Group Innovation 1
Non‐formal learning and tacit knowledge in professional work
Implicit learning and tacit knowledge: An essay on the cognitive unconscious.
Tacit knowledge and the economic geography of context, or The undefinable tacitness of being (there)
Cognition Unawares. (Book Reviews: Implicit Learning and Tacit Knowledge. An Essay on the Cognitive Unconscious.)