AcceptAsync waits for an incoming socket connection without synchronously blocking at the accept call. It returns a Task<Socket>; the task completes when a client connects, yielding a new Socket for that client. A server first binds a listening socket to a port and calls Listen, then awaits AcceptAsync. After handling the connection, the server can await another accept operation. This pattern supports an asynchronous server alongside asynchronous file and socket I/O. section 6.1
Asynchronous file server
A server creates a TCP listening socket, binds it to port 7777, and calls Listen. Inside its loop, `var connection = await listenSocket.AcceptAsync();` obtains each client socket. It then starts asynchronous work for that connection, reading a file with ReadAsync and sending chunks with SendAsync. The accept loop remains available to receive subsequent connections.
