Here I've read the following (translated by Google)
GDP can be calculated in two ways: firstly, by origin, that is, by estimating the value of all goods and services produced, and secondly by the use side, that is, by recording total expenditure on consumer and capital goods, including external trade (the difference between the value of imported and exported goods and services).
These two calculations are always congruent, as consumption adjusted for net exports corresponds to production.
I wonder about one thing: What about all the products being produced but never sold and used: food, clothes, printed media, to name just a few. They appear only on the one side, not on the other. So how can the two numbers be congruent?
And if they are not congruent: Which of them is finally published e.g. by the German Statistisches Bundesamt?