Piracetam's mechanism of action is not fully understood. It is a cyclic derivative of GABA, yet GABA receptors and metabolism appear to not be affected. It is neither, a sedative or a stimulant but is known to influence cognitive ability. Piracetam is also believed to be a vasodilator and a circulatory agent but this is not believed to be its main nootropic action.
Piracetam goes well in combination with other nootropics. This combination is often referred to as a nootropic stack. Naturally, it goes well with a choline source and this is always recommended. Piracetam also stacks well with all the other racetams. Some choose to stack it with other racetams or selected ones. One advantage is that it is fairly cheap as compared to the other racetam nootropics. Piracetam and Aniracetam is a good stack is a very cost effective combination.