Reconciliation
Noun · Development
Definitions
The process by which a UI framework (most notably React) compares the previous virtual DOM tree with the newly rendered one to determine the minimal set of actual DOM mutations needed. React's reconciliation algorithm uses element type and key props to decide whether to update, replace, or unmount components, avoiding expensive full re-renders.
In plain English: How React figures out the smallest number of changes to make on screen when your data updates, instead of redrawing everything.
Example: "Adding a stable key prop to each list item fixed the reconciliation — React was remounting every row on re-render because it couldn't match them up."