Today I learned that there exists a field called Operations Research that is supposed to be a field of mathematics according to sources such as Wikipedia.
Could someone explain to me, what is Operations Research and in what ways is it a field of mathematics?
Operations research (OR) is an interdisciplinary, applied$^{[1]}$ field that is strongly focused in mathematical optimization, and the construction deployment of mathematical models$^{[2]}$ - with the dominating subjects in the field being Linear and Nonlinear optimization (which are also known as Linear Programming and Nonlinear Programming in the field of OR, as there exists a lot of connections with Computer Science).
The origin of Operations Research is quite debated, as some claim that Charles Babbage is the original creator of OR for his work in optimizing the mailing system in England in the 1800's. Nevertheless, every starting story that you will find usually says it started out with an optimization problem that needed to be solved, and by solving that problem it led to the development of some-sort of new subject, or method, that went on to define how we handle optimization problems of the present (George Dantzig is a good example of this, as his invention of the Simplex method in 1947 is still one of the best linear optimization algorithms of the present)
Here is a (non-exhaustive) list of some subjects that are a part of OR:
The mentioned subjects are quite dense by themselves, but someone who is into OR is expected to know some of each subject mentioned above near fluently. In addition, since it is an applied field, a majority of those who are into OR are working to solve real-world optimization problems - with the biggest employers of OR being the military (US Air Force) and large companies (Amazon, Walmart, etc). However, the field does give itself wiggle-room for those who like to develop new algorithmic methods (heuristics and metaheuristics) for unique optimization problems. Here is a thread on some of the recent developments in the field.
Thus, Operations Research can be said to be a part of mathematics as it is foundationally rooted in using the same axioms and methods like any other applied mathematical field. The sole difference between this field and others is that it makes mathematical optimization its sole focus and motive.
Tangential Remarks
$[ 1 ]$ Here is a thread that explains how OR is begin used to solve and assist with other pure math subjects
$[2]$ It cannot be stressed enough how mathematical models are the backbone of OR. While a lot of other fields pre-dating OR structured and used variations of mathematical models to solve their own field-related problems, OR took it several leagues further by unifying the language of the model across multiple fields, and tries to shown that a wide variety of problems of almost all backgrounds are able to be abstracted into models and solved. Half of the beauty from this field is being shocked, and mystified, when someone develops an extremely beautiful model to a complex problem.