A decimal number is a number that uses the base-10 system, which is the standard system for denoting integer and non-integer numbers. It consists of digits ranging from 0 to 9, and it can include a decimal point to separate the whole number part from the fractional part. For example, in the number 12.34, 12 is the whole number, and 34 represents the fractional part. Decimal numbers are commonly used in everyday life, such as in currency, measurements, and calculations. They allow for precise representation of values, making them essential in fields like mathematics, science, and finance. Understanding decimal numbers is fundamental for performing arithmetic operations and interpreting data accurately.