During a request-response lifecycle, your code moves from the server to the client. If you need to access data or resources on the server while on the client, you'll be making a new request to the server - not switching back and forth.
When a new request is made to the server, all Server Components are rendered first, including those nested inside Client Components. The rendered result (RSC Payload) will contain references to the locations of Client Components. Then, on the client, React uses the RSC Payload to reconcile Server and Client Components into a single tree.
Since Client Components are rendered after Server Components, you cannot import a Server Component into a Client Component module (since it would require a new request back to the server). Instead, you can pass a Server Component as props to a Client Component. See the unsupported pattern and supported pattern sections below.
You cannot import a Server Component into a Client Component