What is it?
A modeling language is mainly used in the field of computer science and enginering for designing models of new pieces of software. It is also used to design systemas and devices. A modeling language uses textual and graphical tools to explain and define these sort of things in order to better explain them better.
Why are they important?
As the functional and operational necessities on these systems are expanding, the difficulty to make them is turning into an important factor. As an outcome, these kinds of systems may only be able to be made by the unified effort of people and by the division of labour. Reducing this complexity is very important to succesfully developing whatever system you want.
UML
Easily one of the most famous modeling language. UML is short for Unified Modeling language is a standardized modeling language consisting of a set of diagrams. UML is meant to facilitate communication and reduce confusion among project stakeholders. It helps developers in the task of visualizing, constructing, and documenting the artifacts of software systems, as well as for business modeling and other non-software systems.
References
https://www.visual-paradigm.com/guide/uml-unified-modeling-language/what-is-uml/
http://www.informit.com/store/unified-modeling-language-user-guide-9780321267979
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