The cylinder was rolled over wet clay to mark or identify clay tablets, envelopes, ceramics and bricks. It so covers an area as large as desired, an advantage over earlier stamp seals. Its use and spread coincides with the use of clay tablets, starting at the end of the 4th millennium up to the end of the first millennium. After this time stamp seals are used again.
Cylinder seals are important to historians.
The seals were needed as signature, confirmation of receipt, or to mark clay tablets and building blocks. The invention fits with the needs caused by the general development of city states. Inscriptions are mostly carved in reverse, so as to leave a positive image on the clay with figures standing out. Some are directly carved and leave a negative imprint. However, as the script is largely pictographic, they can at least be partly understood.