The Virtual DOM (VDOM) is a programming concept used in web development that refers to an abstract representation of a web page’s Document Object Model (DOM) structure. In other words, the Virtual DOM is a lightweight copy of the real DOM that can be manipulated more efficiently and with less overhead.

When changes are made to the VDOM, the system compares the previous state of the VDOM with the new state of the VDOM and computes the minimum number of changes necessary to update the real DOM. This process is called “reconciliation,” It enables web applications to update the user interface (UI) more efficiently and with fewer resources than if the real DOM was updated directly.

The Virtual DOM is a popular feature of modern JavaScript frameworks and libraries, such as React and Vue.js, and is often cited as a critical factor in their performance and scalability. By using VDOM, these frameworks can optimize UI updates and deliver fast, responsive web applications.