Fundamental concepts of information theory are introduced to show the applicability of these concepts to the analysis of statistical fluctuations in the neutron density in nuclear reactors. The application of these concepts is illustrated by considering five questions in the field of reactor noise. It is shown that information theory possesses a considerable potential for putting many questions in this field into a more rational theoretical framework and thereby unifying the field. It is also shown that a quantity defined as information can be measured and interpreted.