Our most recognized achievement of the past five years was the realization that disordered proteins have a higher mean energy than globular proteins. Based on this observation the partially or fully disordered proteins or protein segments can be distinguished using the protein sequence alone (see IUPred web server). It allowed to gain valuable insight concerning the intermolecular interactions of disordered proteins. This includes the uncovering of the role preformed structural elements and certain motifs play in protein-protein interactions. Furthermore, it enabled the verification of the abundance of disordered proteins among hubs in protein interaction networks and the significantly high occurrence of protein disorder in essential proteins. These fundamental results enabled the characterization of interacting regions in disordered proteins and the development of a prediction method called ANCHOR for the prediction of such disordered binding sites. We have also demonstrated the functional role of protein disorder in numerous cases, including the analysis of the dUTPase and transglutaminase substrate preference and the mediator complex involved in transcriptional regulation.