So the server would sit there and patiently wait for some buffer space to become available.

And so it says, eh, you've had 15 seconds, you're still not getting any buffer space.

Its campsites have a fair amount of buffer space between them.

Various devices have different amounts of buffer space to hold received characters.

We will consider buffer space as the number of pieces waiting to be worked on.

I mean, they've only got a finite amount of buffer space.

Well, the kernel could block waiting for some buffer space to become available.

So essentially it's a way for one end to probe the other, asking do you have any buffer space yet.

But, oh, by the way, I've got no buffer space, so hold on.

And at that time I've got this much buffer space available.