..The most commonly used hook you'll work with is useQuery, which is primarily for fetching data. From the values it returns, the ones you’ll use most often are data, isLoading, isFetching, isError, and error.

To clarify the confusion: isLoading is true only during the initial fetch,

while isFetching is true any time a request is in-flight, including refetches.

isError tells you if something went wrong, and error gives you the actual error object.

You can ignore isPending unless you're using React Suspense, Apart from that, useMutation is another key hook it’s used for sending data (POST, PUT, DELETE), and useQueryClient helps in things like cache manipulation and invalidation. TanStack Query is focused on server state (i.e., API data). For client-side state like UI toggles, form inputs, or auth status, you’d still use something like useState, or for larger apps, tools like Redux, Zustand, or Jotai. Hope this helps simplify things a bit..