Consumption (C) means private consumption (Private consumption), which include personal expenses, such as rent, food, nearly all of the medication but does not include the purchase of a new home away from home.
Investment (I) means a business investment in capital goods, such as the construction of new mines.To purchase software, purchase equipment, machinery for factories, etc. Spending by households to buy new houses be included in investing as well, thanks to the purchase of financial products such as shares or debentures have not been classified as an investment but as a savings (Saving) everything not included in GDP because it is the only legal document switching only. That the money has not been converted into goods or services. It is not part of the real economy, and be treated as expenditure categories, fund transfer (Transfer payment)
Note: net interest expense of the financial sector is seen as production and create added value and thus be included in GDP.