The "transient receptor potential" (TRP) family of ion channels comprises more than 50 cation-permeable channels expressed from yeast to man. On the basis of structural homology, the TRP family can be subdivided in to seven main subfamilies: the TRPC ('Canonical') group, the TRPV ('Vanilloid') group, the TRPM ('Melastatin') group, the TRPP ('Polycystin'), the TRPML ('Mucolipin'), the TRPA ('Ankyrin') and the TRPN ('NOMP') family. The cloning and characterization of members of this cation channel family has exploded during recent years, leading to a plethora of data concerning TRPs in a variety of cell types, tissues and species. This paper briefly reviews the TRP superfamily and the basic properties of its many members as a reader's guide in this Special Issue. Hopefully, a better understanding of TRP channel physiology will provide important insight into the relationship between TRP channel dysfunction and human diseases.