Blades are defined as being flakes that are at least twice as long as they are wide and that have parallel or subparallel sides and at least two ridges on the dorsal (outer) side. They became the favored technology of the Upper Palaeolithic era, although they are occasionally found in earlier periods. A soft punch or hammerstone is necessary in creating a blade and their long sharp edges made them useful for a variety of purposes. They were often worked to create scrapers or burins.
Cores from which blades have been struck are called blade cores and the tools created from single blades are called blade tools. Small examples (under 12 mm) are called microblades and were used in the Mesolithic as elements of composite tools. Blades with one edge blunted by removal of tiny flakes are called backed blade.