The abacus, also called a counting frame, is one of oldest counting devices. It was developed about 5000 years ago, and it was used by all ancient civilizations. Abacus was used centuries before the adoption of modern numeral system. Abacus consists of wooden frame and rods or wires with freely sliding beads. The beads are usually rounded and made of hardwood or plastic. The beads are counted by moving them towards the rods. Depending of the origin, there are a few slightly different types of the abacus.

Today, abacus is still sometimes used by kids for learning of basic math like add, subtract, multiply, and divide.