IEEE 754 is the fundamental standard for representing floating-point numbers in computer systems. It defines the formats for representing single-precision, double-precision, and extended-precision floating-point numbers. The standard specifies the layout of bits for the sign, exponent, and significand (mantissa) parts of a floating-point number, along with rules for arithmetic operations, special values like infinity and NaN (Not a Number), rounding modes, and handling of exceptions.