To put this in a way the common man can appreciate, imagine you're at a restaurant and you ordered some clam chowder and your waiter brings it to you.

If the waiter brings you the chowder complete in one bowl, you get the chowder then and there. That is HN and most websites from ye olde Web 1.0 days.

Waiter: "Your clam chowder, sir."

You: "Thanks!"

If the waiter brings you the chowder piece by piece, spoon by spoon on the other hand...

Waiter: "Your bowl, sir."

You: "I thought I ordered clam chowder?"

Waiter: "Your clam, sir."

You: "Uhh--"

Waiter: "Another clam, sir."

You: "What are yo--"

Waiter: "Some soup, sir."

You: "..."

Waiter: "An onion, sir."

Waiter: "Another clam, sir."

Waiter: "A potato, sir."

Waiter: "Another onion, sir."

Waiter: "Some more soup, sir."

<An eternity later...>

Waiter: "And your spoon, sir."

You: "What the fuck."