IOTA is an open-source distributed ledger protocol that goes 'beyond blockchain' through its core invention of the blockless ‘Tangle’. The IOTA Tangle is a quantum-proof Directed Acyclic Graph, with no fees on transactions & no fixed limit on how many transactions can be confirmed per second in the network. Instead, throughput grows in conjunction with activity in the network; the more activity, the faster the network. Unlike blockchain architecture, IOTA has no separation between users and validators; rather, validation is an intrinsic property of using the ledger, thus avoiding centralization. IOTA is initially focused on serving as the backbone of the emerging Internet-of-Things (IoT). For a more in depth look at the technical design of IOTA read their https://iota.org/IOTA_Whitepaper.pdf. 

The total supply of IOTA is (3^33 - 1) / 2 = 2,779,530,283,277,761 tokens. This value is optimized for ternary computation - it is the largest possible 33-digit ternary number:

111,111,111,111,111,111,111,111,111,111,111 (base-3) = 2,779,530,283,277,761 (base-10)

The total IOTA token supply was "minted" on the genesis transaction and will never change. It is now impossible for anyone to "mint" or "mine" new IOTA tokens.

IOTA uses the International System of Units (or SI units):