http://en.wikipedia.org/wiki/Money_supplyNote: The examples apply when read in sequential order.
M0
Laura has ten US $100 bills, representing $1000 in the M0 supply for the United States. (MB = $1000, M0 = $1000, M1 = $1000, M2 = $1000)
Laura burns one of her $100 bills. The US M0, and her personal net worth, just decreased by $100. (MB = $900, M0 = $900, M1 = $900, M2 = $900)
M1
Laura takes the remaining nine bills and deposits them in her checking account (current account) at her bank. (MB = $900, M0 = 0, M1 = $900, M2 = $900)
The bank then calculates its reserve using the minimum reserve percentage given by the Fed and loans the extra money. If the minimum reserve is 10%, this means $90 will remain in the bank's reserve. The remaining $810 can only be used by the bank as credit, by lending money, but until that happens it will be part of the banks excess reserves.
The M1 money supply increased by $810 when the loan is made. M1 money has been created. ( MB = $900 M0 = 0, M1 = $1710, M2 = $1710)
Laura writes a check for $400, check number 7771. The total M1 money supply didn't change, it includes the $400 check and the $500 left in her account. (MB = $900, M0 = 0, M1 = $1710, M2 = $1710)
Laura's check number 7771 is accidentally destroyed in the laundry. M1 and her checking account do not change, because the check is never cashed. (MB = $900, M0 = 0, M1 = $1710, M2 = $1710)
Laura writes check number 7772 for $100 to her friend Alice, and Alice deposits it into her checking account. MB does not change, it still has $900 in it, Alice's $100 and Laura's $800. (MB = $900, M0 = 0, M1 = $1710, M2 = $1710)
The bank lends Mandy the $810 credit that it has created. Mandy deposits the money in a checking account at another bank. The other bank must keep $81 as a reserve and has $729 available for loans. This creates a promise-to-pay money from a previous promise-to-pay, thus the M1 money supply is now inflated by $729. (MB = $900, M0 = 0, M1 = $2439, M2 = $2439)
Mandy's bank now lends the money to someone else who deposits it on a checking account on yet another bank, who again stores 10% as reserve and has 90% available for loans. This process repeats itself at the next bank and at the next bank and so on, until the money in the reserves backs up an M1 money supply of $9000, which is 10 times the M0 money. (MB = $900, M0 = 0, M1 = $9000, M2 = $9000)
M2
Laura writes check number 7774 for $1000 and brings it to the bank to start a Money Market account (these do not have a credit-creating charter), M1 goes down by $1000, but M2 stays the same. This is because M2 includes the Money Market account in addition to all money counted in M1.
Foreign Exchange
Laura writes check number 7776 for $200 and brings it downtown to a foreign exchange bank teller at Credit Suisse to convert it to British Pounds. On this particular day, the exchange rate is exactly USD 2.00 = GBP 1.00. The bank Credit Suisse takes her $200 check, and gives her two £50 notes (and charges her a dollar for the service fee). Meanwhile, at the Credit Suisse branch office in Hong Kong, a customer named Huang has £100 and wants $200, and the bank does that trade (charging him an extra £.50 for the service fee). US M0 still has the $900, although Huang now has $200 of it. The £50 notes Laura walks off with are part of Britain's M0 money supply that came from Huang.
The next day, Credit Suisse finds they have an excess of GB Pounds and a shortage of US Dollars, determined by adding up all the branch offices' supplies. They sell some of their GBP on the open FX market with Deutsche Bank, which has the opposite problem. The exchange rate stays the same.
The day after, both Credit Suisse and Deutsche Bank find they have too many GBP and not enough USD, along with other traders. Then, To move their inventories, they have to sell GBP at USD 1.999, that is, 1/10 cent less than $2 per pound, and the exchange rate shifts. None of these banks has the power to increase or decrease the British M0 or the American M0; they are independent systems.