The term “in situ” is a Latin term, which means “in its original place”. Situ is derived from the Latin “situs”, which means “a place, position, situation, site, location, or station”. The term “in situ” emphasizes that the thing in question is situated in its natural or original or proper place or position. Although this term is frequently used in biology and medical science, its usage is not limited to these fields. For an example, a benign or non-malignant tumor confined or localized to its original location of development in the body is described as an in situ tumor. Other example of usage of in situ that can be cited here is: discovery of an ancient object such as a piece of pottery at an excavation site. Here, the object is said to be found in situ. In engineering, a part of a machine is tested in situ, that is, at its original place of operation or functioning, which is in the machine itself.