This paper discusses several features of knowledge that are often considered crucial for characterizing the economic significance of knowledge: whether it is overtly accessible or tacit, whether it can be or is encoded or not, and whether it has public or private good character. It is argued that all these features depend similarly on the state of the knowledge technology, i.e. on how knowledge can be acquired, stored, used, and communicated. The different characteristics and the relationships between them are shown to correspond to different specifications of the technology, specifications that are not always made explicit in the literature.