Gdp excludes most items that are produced and sold illegally and most items that are produced and consumed at home because

Gdp excludes the most of items that are produced and sold illegally and also most of the items that are produced and consumed at home because the products which are illelegal are not sold under government policies and are not authorised.

Explanation:

GDP: It is been referred as the total value of all the goods and services which has been produced for the marketplace within one year's period and within our national borders.

Measurment of GDP:

It will record only the value of final output of goods no intermediate goods are included in it. The output here is valued only at its market prices. It measures the values of both tangible and intangible services. It measures the values of goods which are produced within the geographic boundaries of country.

Where this GDP is countable:

It is countable only where the products are produced in economy and are being sold legally in the markets.

Excludes the products being sold illegally.