Algorand’s clean and fast blockchain
A traditional blockchain is elongated via an expensive probabilistic process. Multiple users compete for the production of the next block by trying independently to solve a hard cryptographic puzzle. The chance thus exists that two or more of them succeed within a few seconds of each other. In this case, a fork is generated: that is, at least two blocks B and B’ can be viewed as being the latest added block and the blockchain branches. Eventually, only one branch will continue to be part of the longest chain, while the other will be discarded. Accordingly, a user cannot rely on the transactions contained in the latest block. Such uncertainty is problematic in most financial applications, where the fast finality of transactions is essential. Of course, a user may wait that a new block becomes deep enough in the chain, if she wants to be certain that it will continue to be part of the longest chain. But this only increases the latency of the system, making it inapplicable for many use cases.
By contrast, Algorand has no forks. Better said, the probability of a fork can be as low as 10-18. Recall that 1018 is the estimated number of seconds from the Big Bang to now. In other words, if a block were produced every second, then one would have to wait for the age of the Universe to see a fork in Algorand. Therefore, in Algorand, one can safely rely on a new block as soon as it appears, and all transactions contained in it are final. Moreover, Algorand consensus protocol certifies a block every few seconds, resulting in a very low latency.