Prajnaparamita — prajna (wisdom) + paramita (perfection) — names both a family of Mahayana sutras (composed between roughly 100 BCE and 500 CE) and the practice they transmit: the direct seeing of Emptiness.
The most famous of these sutras are the Heart Sutra (the shortest) and the Diamond Sutra. Longer versions run to 100,000 verses. All work the same rhetorical pattern — affirming categories, then emptying them — to produce in the reader a suspension of conceptual grip.
Prajnaparamita is the sixth of the six perfections cultivated by a Bodhisattva, and the one without which the other five (generosity, ethics, patience, energy, meditation) cannot be complete.