Does an ACK means all the data have been read by the receiver application in TCP?

Question

When I am reading something about TCP three-step connection, two questions popped out in my mind:

1. If there is an receive window in receiver, is an ACK sent back when one received data is stored into the window or when the window is full?

2. When the sender receives an ACK, does it mean that all the sent data have been read and processed by the receiver application?

Actually, these two questions have several inner connections. Thanks for any helpful answers!

Answer 1

No. The ACK simply means that the data has arrived in the TCP stack of the peer. This does not indicate that the application has read and processed the data.