This volume grew out of the various oral and poster presentations given during the "Evaporite" session at the International Geological Union conference (2004) in Florence, Italy. It was clear that only a few of the participants or attendees, coming from many countries and various distant parts of the world, were well informed about evaporites outside their immediate area of study, apart from data from the most commonly available literature. Diversity in the languages of publication and the logistical difficulty of making first-hand comparisons acts as a major barrier to study. As a result, the basic concept of evaporites that most geologists have is that deposits are the product of simple, chemically controlled environments and, if evaporitic compounds are chemically the same, then it follows that their lithology and origin are also the same. Based on many studies over the past 30 years, it is now clear that this long-held impression is manifestly untrue. The disparities were very evident in the photographic presentations and descriptions at the 2004 International Geological Congress: the same evaporitic compounds can have distinct and diverse lithology, depositional sources and geological history. They cannot be considered to arise solely from simple, direct chemical origins as explained by a single universal model! This is the same paradigm of sedimentation that functions with other deposits, such as siliciclastics and carbonates, and should also apply to evaporites. In putting this volume together, we realized there were many questions about evaporites from parts of the world not discussed in Florence, despite the large number of participants. Thus, in order to broaden and balance the topics already in our Congress program, we added two additional review papers. One paper that we have added is a chapter covering the many evaporites in the former Soviet Union territory: Russia, Ukraine, Belarus and Moldova. This...