A modern version of monetary circuit theory with a particular emphasis on stochastic underpinning mechanisms is developed. It is explained how money is created by the banking system as a whole and by individual banks. The role of central banks as system stabilizers and liquidity providers is elucidated. It is shown how in the process of money creation banks become naturally interconnected. A novel extended structural default model describing the stability of the interconnected banking network is proposed. The purpose of bank capital and liquidity is explained. Multi-period constrained optimization problem for bank balance sheet is formulated and solved in a simple case. Both theoretical and practical aspects are covered.