Purpose In line with the cognitive viewpoint on the phenomenon of information, the constructivist tradition based on Maturana and Varela's theory of knowing, and some aspects of Shannon's theory of communication, the purpose of this paper is to shed more light on the role of information, data, and knowledge in the cognitive system (domain) of the observer. Design/methodology/approach In addition to the literature review, a proposed description of the communication and knowledge acquisition processes within the observer's cognitive system/domain is elaborated. Findings The paper recognizes communication and knowledge acquisition as separate processes based on two roles of information within the observer's cognitive system, which are emphasized. The first role is connected with the appropriate communication aspects of Shannon's theory related to encoding cognitive entities in the cognitive domain as data representations for calculating their informativeness. The second role involves establishing relations between cognitive entities encoded as data representations through the knowledge acquisition process in the observer's cognitive domain. Originality/value In this way, according to the cognitive viewpoint, communication and knowledge acquisition processes are recognized as important aspects of the cognitive process as a whole. In line with such a theoretical approach, the paper seeks to provide an extension of Shannon's original idea, intending to involve the observer's knowledge structure as an important framework for the deepening of information theory.