The literature related to the three-dimensional ﬁbre networks is reviewed since 2000. Indeed, a review was presented in these symposia in 2001 . Therefore, the updated articles are only considered here. The previous review concentrated on theory, whereas the focus here is on modern 3D analysis and comparisons of these with theory. Moreover, the focus is on paper structure. However, the general context of 3D structure is considered in the introduction in order to illustrate the main ideas that may be applied to paper. Then, the experimental methods are presented in order to show the potential of such techniques. In a third part, improvements of the description of the 3D structure will be presented. Namely, the quantitative description that completes the visualisation of the structures will be presented. The main 3D morphological properties will be presented and some examples will illustrate the existing developed tools. The Representative Elementary Volume (REV) dedicated to the structure properties will then be introduced. The theoretical models are brieﬂy presented to prove the necessary development of both experimental tools and dedicated theories. Theoretical studies will be exempliﬁed. Indeed, both theoretical and experimental demarches will enrich each other as will be shown. The inﬂuence of both deformation and humidity modiﬁcations on the 3D structure will illustrate the interest of the knowledge of the 3D structure, to tackle its inﬂuence on physical properties. The main perspectives and challenges related to the structure description will end up this presentation.