insitu

In situ is a Latin expression meaning "in its original place" or "in position." In academic and scientific usage, it indicates that something is observed, measured, or preserved at the location where it naturally occurs, rather than being moved or removed to another setting.

In ecology and conservation, in situ refers to actions that occur within the natural habitat of a species. In situ conservation aims to protect populations in their native environment, as opposed to ex situ approaches that maintain organisms in captivity or in controlled facilities. In archaeology and art history, in situ means an object remains in its original place; its context and provenance rely on its current location.

In geology and environmental science, in situ describes measurements or processes observed directly at the site. Examples include in situ soil analyses, in situ spectroscopy or imaging during a reaction, and in situ remediation techniques that treat contamination without removing material from the environment.

In medicine and pathology, the term appears in contexts such as carcinoma in situ, where abnormal cells are present but confined to the site of origin. In situ techniques also include in situ hybridization and other analyses performed within intact tissues.

Although often written as two words (in situ) in formal writing, some modern contexts use insitu as a single word. The term is widely used across disciplines to emphasize the realism of location, timing, and context, and it is commonly contrasted with ex situ or ex situ approaches.