In the simple and popular term, React is the V (View) in MVC (Model/View/Controller).
Some of the concepts under which React operates:
Reusable, composable, and stateful components:
In React, we build HTML views using smaller components. We can reuse a single component in multiple places, with different state and properties, and every component can contain other components. All components in React have a state that may change over time, and React will take care of updating the components’ views when their state changes.
The nature of reactive updates:
React’s name is the simple explanation for this concept. When the state of a component changes, those changes need to be reflected somewhere, for example, if we’re writing HTML components for a browser, we need to regenerate the HTML for the browser’s DOM (Document Object Model). With React, we do not have to worry about how to reflect the state changes, React will simply react to the changes and update views as needed.
The virtual representation of views in memory: