DOM stands for Document Object Model .This is a programming API for HTML and XML documents. It defines the logical structure of documents and the way a document is accessed and manipulated.With the Document Object Model, programmers can create and build documents, navigate their structure, and add, modify, or delete elements and content.
The name “Document Object Model” was chosen because it is an “object model” is used in the traditional object oriented design sense: documents are modeled using objects, and the model encompasses not only the structure of a document but also the behavior of a document and the objects of which it is composed. In other words, the nodes in the above diagram do not represent a data structure, they represent objects, which have functions and identity.
If you want to get more details then visit this link
https://www.w3.org/TR/WD-DOM/introduction.html