Primary retention is the perception of objects that are present in the environment. Secondary retention is the recollection of primary retentions, or direct perceptions. Tertiary retention, usually traced to Bernard Stiegler’s work, is memory that has been exteriorised and inscribed in material forms that transmit knowledge and affect across space and time.

Tertiary retentions extend beyond the individual, the group and beyond established social and cultural practices associated with a specific epoch. They form a lasting ‘reserve’ inscribed in databases, recorders, gadgets and networks.