The amount of money that is laundered each year is around $800 billion dollars to as much as $2 trillion dollars every year.
Some examples of money laundering which is illegal are casino schemes, business schemes, smurfing schemes, and foreign investment/round-tripping schemes.
The definition of money laundering is the concealment of the origins of illegally obtained money, typically by means of transfers involving foreign banks or legitimate businesses.
The money is laundered and concealed to help the person avoid paying taxes on that money.
If caught you can face huge fines as well as jail or prison time.
Money laundering is taken seriously by the law so you should never do any money laundering.