[galaxyLogic]

A good resource thanks. "It measures the total value of all goods and services produced".

But so then if I produce nothing but just sell something at profit which I already have is that part of the GDP?

If the value of my stamps-collection increases and I sell it at considerable profit is that an increase in GDP?

[PeterisP]

In general, the added value would be part of the GDP - e.g. a retailer would be considered to contribute its revenue minus the wholesale cost of goods, rent, salaries, etc which was already counted as produced by its suppliers.