Markov Chain Monte Carlo (MCMC)

It has, perhaps, been IOTA’s greatest success to communicate what is a complicated and non-standard technology amid the broad umbrella of blockchain.

They run on a Directed Acyclic Graph (DAG) architecture -- dubbed the ‘Tangle’ -- and use MCMC to achieve consensus. This is a complex algorithm which is best understood by statisticians but the concept is straightforward when applied.

After a user broadcasts their transaction, the algorithm randomly selects two unconfirmed transactions to verify. With IOTA, a small amount of Proof-of-Work is needed to confirm these transactions, and the user’s own broadcast can then be verified by someone else.

IOTA will initially use ‘coordinators’, or master nodes, who act as a network failsafe by ensuring any fraudulent transactions and attacks can be dismissed. Additionally, no mining means a massive boost to energy efficiency.

Matrix also proposes to use MCMC, as do BigTangle whose construct seems similar in design to IOTA though perhaps slightly less fleshed out.