The article discusses the classification of intrinsically disordered regions (IDRs) and proteins, emphasizing their functional diversity and importance in biological processes. It highlights that many proteins are not structured but still functional, with IDRs playing a key role in various biological functions. These regions are characterized by their flexibility and ability to interact with other molecules, enabling functions such as molecular recognition, assembly, and regulation. The classification of IDRs and proteins is crucial for understanding their functions and improving function prediction. The article outlines different functional classes of IDRs, including entropic chains, display sites, chaperones, effectors, assemblers, and scavengers. It also discusses the structural and sequence characteristics of IDRs, their role in protein interactions, evolution, and regulation. The classification of IDRs and proteins is essential for annotating their functions and improving our understanding of protein function. The article provides an overview of various classification schemes and resources available for studying IDRs and proteins, emphasizing the need for further research to enhance function prediction and annotation.The article discusses the classification of intrinsically disordered regions (IDRs) and proteins, emphasizing their functional diversity and importance in biological processes. It highlights that many proteins are not structured but still functional, with IDRs playing a key role in various biological functions. These regions are characterized by their flexibility and ability to interact with other molecules, enabling functions such as molecular recognition, assembly, and regulation. The classification of IDRs and proteins is crucial for understanding their functions and improving function prediction. The article outlines different functional classes of IDRs, including entropic chains, display sites, chaperones, effectors, assemblers, and scavengers. It also discusses the structural and sequence characteristics of IDRs, their role in protein interactions, evolution, and regulation. The classification of IDRs and proteins is essential for annotating their functions and improving our understanding of protein function. The article provides an overview of various classification schemes and resources available for studying IDRs and proteins, emphasizing the need for further research to enhance function prediction and annotation.