An abacus is one of the earliest tools used for calculation. It is a simple counting device made of a frame with rods and movable beads. Each bead represents a number, and by sliding the beads back and forth, you can perform basic arithmetic like addition, subtraction, multiplication, and division.

Before calculators and computers, traders and accountants used the abacus to quickly calculate totals, prices, and accounts. It helps users understand place value (units, tens, hundreds) clearly and improves mental math skills.

In short, an abacus is a manual calculating tool that helps perform arithmetic operations using beads.