The Decimal Number System is a base-10 numeral system that uses ten digits: 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9. Each digit's position in a number represents a power of ten, which helps in understanding the value of the number. For example, in the number 345, the 3 represents 300, the 4 represents 40, and the 5 represents 5. This system is widely used in everyday life, from counting and measuring to financial transactions. The Decimal Number System is essential for mathematics and is the foundation for more complex systems, such as fractions and decimals.