Money On Chain is a suite of smart contracts whose purpose is providing:
A bitcoin-collateralized stable-coin, Dollar On Chain, (DoC)
A passive income hodler-targeted token, BitPro (BPRO)
A leveraged Bitcoin investment instrument (BTCX series).
The rationale behind this is that deposits of RBTC help collateralize the DoCs, BitPro absorbs the USD-BTC rate fluctuations, and BTC2X is leveraged borrowing value from BitPro and DoC holders, with a daily interest rate being paid to the former.
Note in this tutorial we will use BTC and RBTC as interchangeable terms, as there is a 1:1 peg guaranteed by the RSK network, but in all the cases we mean RBTC as this is the correct coin of the RSK token.
MoC system is a network of cooperative smart contracts working together to ultimately provide a US dollar pegged ERC20 Token (DoC). In this sense, the contracts we can categorize them into 4 categories:
MoC state Contracts: They keep MoC state variables and logic (MoC, MoCState, MoCBucketContainer, MoCSettlement)
MoC pure logic Contracts & Libraries: Functional extensions of the above merely to have responsibility separation and contracts size (aka deploy fee) low. (MoCHelperLib, MoCLibConnection, MoCConverter, MoCExchange, MoCConnector, MoCBProxManager, MoCInrate, MoCWhitelist, MoCBase)
Tokens: Tokens backed by the system (OwnerBurnableToken, DocToken, BProToken, MoCToken)
External Dependencies: External contracts the system relies on, in this case the Oracle or price provider; this could evolve independently of MoC system as along as the interface is maintained. (PriceProvider)
Also you can read official information about MoC architecture and Money on Chain's smart contracts