What does an "Ack" mean in Apache Storm/Hadoop?

Question

Can someone tell me what an "Ack" means for Apache Storm/Hadoop? Does it mean that you "ack" a tuple when it is considered complete and didn't fail? Removing it from the queue similar to how an ESB removes messages after processing them? Where did that weird word come from and does it stand for something? I looked here but was still a bit confused: https://storm.apache.org/documentation/Concepts.html

Answer 1

As far as "Ack" in Apache Storm context, it lets the originating Spout know that the tuple has been fully processed.

If Storm detects that a tuple is fully processed, Storm will call the ack method on the originating Spout task with the message id that the Spout provided to Storm.

Link

It's a way to guarantee that a specific tuple has made it all the way threw the topology.