A number system is a way to represent and organize numbers. The most common system is the decimal system, which uses ten digits (0-9) to express all numbers. Other systems include the binary system, which uses only two digits (0 and 1), and the hexadecimal system, which uses sixteen symbols (0-9 and A-F). Each system has its own rules for combining digits to form larger numbers. Number systems are essential in mathematics and computer science. They help in performing calculations, coding information, and understanding numerical relationships. For example, computers primarily use the binary system to process data, while humans typically use the decimal system for everyday counting and calculations.