Why is the Bitcoin blockchain designed so that a block can be unconfirmed?
Why is the Bitcoin blockchain designed so that a block can be unconfirmed? I have a basic question about blockchain and Bitcoin. After a transaction is confirmed and included in a block, it is said to have a depth (confirmation) of one. However I've read that many companies require "multiple" confirmations (up to 6) before they consider a transaction truly confirmed. Does that mean that a block taht is confirmed can be revoked, thus nullifying the previously confirmed transaction? What purpose would such a behavior serve -- in other words, once a transaction is confirmed and a block is formed, what advantage is there to later "unconfirmed" taht block? http://ift.tt/2BRxhsa