Smartbomb
A guided bomb (also known as a smart bomb, guided bomb unit, or GBU) is a precision-guided munition designed to achieve greater accuracy.
Because the damage effects of explosive weapons fall off with distance according to a power law, even modest improvements in accuracy (and hence reduction in miss distance) enable a target to be effectively attacked with fewer or smaller bombs. Therefore, with guided weapons, fewer air crews are put at risk, less ordinance spent, and collateral damage reduced.
The creation of precision-guided munitions resulted in the retroactive renaming of older bombs as unguided bombs or "dumb bombs".