Tacit knowledge (as opposed to formal or explicit knowledge) is the kind of knowledge that is difficult to transfer to another person by means of writing it down or verbalising 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. However, the ability to speak a language, use algebra,
or design and use complex equipment requires all sorts of knowledge that is not always known explicitly, even by expert practitioners, and which is difficult to explicitly transfer to users.
While tacit knowledge appears to be simple, it has far reaching consequences and is not widely understood.