Today, all experts believe that knowledge and the extent to which it is accessible are main factors distinguishing the 21st century organizations from each other. Knowledge is a human category resulting from interpersonal interactions. Different views have been stated about knowledge. In studies, it has been divided into two types: explicit and tacit while the importance of the latter got emphasized. But it seems that there is no consensus on concepts and differences of these two types, as some of views are inconsonant and against each other. Since tacit knowledge is a strong point for organizations as well as a factor to gain competitive privilege in the present era, great efforts have been made by organizations to gain this important knowledge worldwide. In this regard some focused on production while others on sharing and transferring it. Although it costs them too much, the desired results may not always be achieved. The reason is the lack of any exact definition for tacit knowledge; the one that could reveal the real nature of it in order to draw up a scheme for producing, transferring and sharing it. The producing, transferring and sharing the tacit knowledge becomes a vague, difficult activity if there is not an appropriate perception about it. Therefore, good understanding of this concept is a key factor to solve such problems. In this article, the review of the literature, related to explicit and tacit knowledge as well as new perspectives will be presented; a view that may clarify the unclear points of previous studies and increase the speed of producing, transferring and sharing tacit knowledge.