Liquid process, which uses the nature of liquid to produce products, is first identified and assigned as a technical term. When a liquid process is applied for fabricating devices, there are two cases: one where the liquid process is only used for making films and the other where it is used not only for making films but also for patterning them simultaneously. As the technology of the latter case totally depends on the former, we call the former case the first step and the latter one the second step. The first step can be interpreted as a conversion process from liquid to solid. Here all the conversion methods from liquid to solid, which have been ever known, are addressed and classified and their advantages and disadvantages clarified in terms of device fabrication. Then, direct forming processes as the second step are described related to the printed electronics (PE) technology. Inherent problems of PE when applied for device fabrication are addressed and the objective of the project (ERATO Shimoda nano liquid process project) is clarified.