Of the phenomena which occur at the interface between a solid and a liquid, common examples include the deposition and corrosion of metals, the charging and discharging of storage batteries, and the wet processing of semiconductor devices. Developments in STM operated at solid-liquid interfaces led to its valuation as arguably the premier technique for atomic-level surface structural investigations of chemical processes taking place at solid-liquid interfaces. The present article describes a brief current status of in situ STM.