"Decimal" usually refers to a data type which is "integer, shifted by a known number of decimal places". So, for example, if you had an amount of money $123.45,

"Decimal" usually refers to a data type which is "integer, shifted by a known number of decimal places". So, for example, if you had an amount of money $123.45, you could represent that as a 32-bit floating point number with (sign=0 (positive), exponent=133, mantissa=7792230) which is 123.4499969482421875, but you would probably be better off representing it with a decimal type which represents the number as (integer part=12345, shift=2), or as just a straight integer number of cents. The number base is relevant, because money is discrete, and measured in units of exactly 1/10^n, and if you try to use floating point numbers to represent that you will cause your future self a world of pain.