An aim of this paper is to clarify what the knowing-that/knowing-how distinction means. First, we summarize characteristics of knowing-that and knowing-how in Ryle (1949). Next, we address the recent discussions on this distinction. Especially, we examine a bold claim made by Stanley and Williamson, namely the claim that knowing-how is a species of knowing-that. In the last part of this paper, we reorganize these discussions by introducing a distinction between internalism and externalism of knowing-that. We conclude that knowing-how cannot be reduced to knowing-that. But this does not mean that they are completely separated. Some knowing-that presuppose some knowing-how, and vice versa.