React creates a virtual DOM. When state changes in a component it firstly
runs a “diffing” algorithm, which identifies what has changed in the virtual
DOM. The second step is reconciliation, where it updates the DOM with the
results of diff.
The HTML DOM is always tree-structured — which is allowed by the
structure of HTML document. The DOM trees are huge nowadays because of
large apps.
The Virtual DOM is an abstraction of the HTML DOM. It is lightweight and
detached from the browser-specific implementation details.
