Strategic investment. Foreign aid helps countries whose interests align with our own increase their capacities. The United States gives money to help select countries -- not the entire world -- improve specific abilities, like their ability to provide public security, defend their borders, or buy and sell goods.
The U.S. is not trying to change people's heart or minds, contrary to the bribery view. It is only trying to change their capacity. Additionally, this view helps the U.S. prioritize which countries should get aid, and what kind, contrary to the charity view.