During a IBD : Initial Block Download by a full node, from where is the blockchain downloaded? I understand that a full node requires to do an IBD before being able to verify transactions. So, it downloads the ledger upto now, which is known as Initial Block Download.
But what I don't understand/know is, from where is the blockchain information being downloaded? Are other full nodes contributing in this activity, or is this information stored somewhere, and is retrieved from there?
Any help appreciated!
Yes, they download blocks from other nodes they connect to.
In Bitcoin Core you have the choice between being a pruned node or not. In both cases all blocks are downloaded and fully verified, but in pruned mode old blocks are deleted after a while after being verified. This has a number of implications, but one of them is that a pruned node does not help new nodes perform IBD.