Polynomial Function:A polynomial function is a function that can be expressed as the sum of a finite number of non-negative integer powers of the independent variable, with real number coefficients.
Complex Numbers:Complex numbers are a number system that extends the real number system to include the imaginary unit $i$, where $i^2 = -1$. Complex numbers can be expressed in the form $a + bi$, where $a$ and $b$ are real numbers.
Roots of a Polynomial: The roots of a polynomial are the values of the independent variable that make the polynomial function equal to zero. The Fundamental Theorem of Algebra guarantees the existence of at least one complex root for every non-constant polynomial.