Route params are the parsed values from a dynamic segment.
<Route path="/concerts/:city" element={<City />} />
In this case, :city is the dynamic segment. The parsed value for that city will be available from useParams
import { useParams } from "react-router";
function City() {
  let { city } = useParams();
  let data = useFakeDataLibrary(`/api/v2/cities/${city}`);
  // ...
}
Search params are the values after a ? in the URL. They are accessible from useSearchParams, which returns an instance of URLSearchParams
function SearchResults() {
  let [searchParams] = useSearchParams();
  return (
    <div>
      <p>
        You searched for <i>{searchParams.get("q")}</i>
      </p>
      <FakeSearchResults />
    </div>
  );
}
React Router creates a custom location object with some useful information on it accessible with useLocation.
function useAnalytics() {
  let location = useLocation();
  useEffect(() => {
    sendFakeAnalytics(location.pathname);
  }, [location]);
}
function useScrollRestoration() {
  let location = useLocation();
  useEffect(() => {
    fakeRestoreScroll(location.key);
  }, [location]);
}