Aerospace: In the aerospace industry, equipment on board aircraft must be tested "in situ", or in place, to confirm everything functions properly as a system. Individually, each piece may work but interference from nearby equipment may create problems not anticipated. Special test equipment is available for this "in situ" testing.

Archaeology: In archaeology, "in situ" refers to an artifact that has not been moved from its original place of deposition. In other words, it is stationary, meaning "Still". An artifact being "in situ" is critical to the interpretation of that artifact and, consequently, to the culture which formed it. Once an artifact's 'find-site' has been recorded, the artifact can then be moved for conservation, further interpretation and display. An artifact that is not discovered "in situ" is considered out of context and will not provide an accurate picture of the associated culture. However, the out of context artifact can provide scientists with an example of types and locations of "in situ" artifacts yet to be discovered.

"In situ" only expresses that the object has not been "newly" moved. Thus, an archaeological in-situ-find may be an object that was historically looted from another place, an item of "booty" of a past war, a traded item, or otherwise of foreign origin. Consequently, the "in situ" find site may still "not" reveal its provenance but with further detective work may help uncover links that otherwise would remain unknown. It is also possible for archaeological layers to be reworked on purpose or by accident (by humans, natural forces or animals). For example, in a "tell-tell mound", where layers are not typically uniform or horizontal, or in land cleared or tilled for farming.

The term "In situ" is often used to describe ancient sculpture that was carved in place such as the Sphinx or Petra.

Architecture: in situ means construction which is carried out on the building site using raw materials. Compare that with prefabricated construction, in which building components are made in a factory and then transported to the building site for assembly. For example, concrete slabs may be in situ or prefabricated.

In situ techniques are often more labour-intensive, and take longer, but the materials are cheaper, and the work is versatile and adaptable. Prefabricated techniques are usually much quicker, therefore saving money, but factory-made parts can be expensive. They are also inflexible, and must often be designed on a grid, with all details fully calculated in advance. Finished units may require special handling due to excessive dimensions.

Art: In art, in situ refers to a work of art is made specifically for a host site, or that a work of art takes into account the site in which it is installed or exhibited.

Astronomy: Future space exploration or terraforming may rely on obtaining supplies in situ, such as previous plans to power the Orion space vehicle with fuel minable on the moon.
Mars Direct mission concept is based primarily on the in situ fuel production using Sabatier reaction.

A fraction of the globular star clusters in our Galaxy, as well as those in other massive galaxies, might have formed in situ. The rest might have been accreted from now defunct dwarf galaxies.

Biology:  in situ means to examine the phenomenon exactly in place where it occurs (i.e. without moving it to some special medium). This usually means something intermediate between in vivo and in vitro. For example, examining a cell within a whole organ intact and under perfusion may be in situ investigation. This would not be in vivo as the donor is sacrificed before experimentation, but it would not be the same as working with the cell alone (a common scenario in in vitro experiments).

In-vitro was the first of mankind’s attempts to qualitatively and quantitatively analyze natural occurrences in the lab. Eventually, the limitation of in-vitro experimentation was that they were not conducted in natural environments. To compensate for this problem, in-vivo experimentation allowed testing to occur in the originate organism or environment. To bridge the dichotomy of benefits associated with both methodologies, in-situ experimentation allowed the controlled aspects of in-vitro to become coalesced with the natural environmental compositions of in-vivo experimentation.

In oncology: for a carcinoma, in situ means that malignant cells are present as a tumor but has not metastasized, or invaded, beyond the original site where the tumor was discovered. This can happen anywhere in the body, such as the skin, breast tissue, or lung.

In conservation of genetic resources, "in-situ conservation" (also "on-site conservation") is the process of protecting an endangered plant or animal species in its natural habitat, as opposed to ex-situ conservation (also "off-site conservation").