Explicit and tacit knowledge are important parts in the knowledge management. I thought that tacit knowledge should be converted to explicit in forms of documents, online databases, patents, and etc, then the knowledge can be expressed. When I read the modes of knowledge conversion on "knowledge managment: classic and contemporary works" by Morey et al., I realized that there are other modes of knowledge conversion. Four modes of knowledge conversion are: from tacit to tacit, which is called socialization; from tacit to explicit, or externalization; from explicit to explicit, or combination; and from explicit to tacit , or internalization.
Other three modes:
From tacit to tacit is a process sharing experiences. People can gain tacit knowledge directly from others without using language, especially when people have the similar experiences. If lack of the shared experiences, it is very difficult for a person to understand another person's thinking process.
From explicit to explicit is a process of systemizing concepts into a knowledge system. People exchange their knowledge and combine them together through media such as meetings, telephon conversation, emails and so on. This knowledge conversion is most often see in the business.
From explicit to tacit is a process of embodying explicit knowledge into tacit knowledge. It is just like "learning by doing". When experiences through socialization, externalization, and combination are internalized into people's tacit knowledge bases in the form of shared mental models, they become valuable assets.