As apps grow, some client state needs to be shared widely — a cart, UI preferences, authentication, a sidebar's open state — across components that are not neatly parent and child. Context can do this but re-renders every consumer on any change, and lifting state high causes prop drilling and bloated components. A dedicated state-management library solves shared client state cleanly, and Zustand has become a favourite for its minimalism.
Zustand lets you create a store — a single object holding state and the functions that update it — outside the component tree, then read from it in any component with a hook. Crucially, components select just the slice they need, and only re-render when that slice changes, giving the fine-grained subscriptions context lacks, with almost no boilerplate and no provider required.
This lesson covers creating a Zustand store, selecting state with selectors, defining actions, and middleware like persistence. It also clarifies what belongs in a client-state store versus the server-state cache (TanStack Query) from the previous module — a distinction that keeps state architecture clean as an application scales.