I'm new to blockchain field and I read one article. article
In this article of Authorization chapter, it is said that "For a public blockchain, the decision to add a transaction to the chain is made by consensus. This means that the majority of “nodes” (or computers in the network) must agree that the transaction is valid."
But, I can't imagine the agreement situation by nodes.
How do all nodes agree on that new block should be added to blockchain ? Do nodes have to agree or disagree manually like by clicking a "Agree!!" or "Disagree!!" button?
Also, doesn't it take soooooo long time? I mean that there are tons nodes in the network and to gather all nodes agreement, it'll be sooooo long time I guess.