This essay reviews conceptual as well as historical backgrounds of public opinion and emphasizes the relevance of phenomenological perspectives for public opinion research. The phenomenological concepts, such as being-in-the-world, intersubjectivity, intercorporeality, communicative reason, and in-betweens, become all the more relevant to public opinion research than ever. The reason is that the essential nature of the interactive digital communication technologies, on which contemporary public opinion formations are based, can be adequately captured by the phenomenological concepts. Particularly, this essay focuses on the relevance of Heidegger's concept of Dasein, or being-in-the-world, for better understanding of the nature of public opinion in the age of the Internet and the digital media.