Make your UI automatically respond when the data behind it changes.
Reactivity is what makes a Svelte interface update when its underlying state changes. Svelte tracks the relationships between your component state and the UI so it knows when something needs to be updated.
The exact way reactivity works depends on the Svelte version and syntax you are using. Understanding reactive state, derived values, and updates is important because it helps you build components without manually forcing the UI to refresh.
What you'll walk away knowing