Investment accounts for business inventory and spending on factors of production. Computers that a firm purchases for its office accounts for investment spending. Meanwhile, all unsold goods (business inventory) counts as investment spending. If inventory items get purchased in the same year, the value of the item moves from Investment to Consumption, causing no change to overall GDP. Note that wages paid are not included in investment, since these wages are what households use for Consumption.
" investing" does not count as investment
Investment instruments (stocks, index funds, bonds, etc) are NOT counted in the investment component of GDP.