A polynomial root is a value of the variable that makes a polynomial equation equal to zero. For example, in the polynomial equation f(x) = x² - 4, the roots are x = 2 and x = -2 because substituting these values into the equation results in zero. Finding the roots of a polynomial is essential in various fields, including mathematics, engineering, and physics. Techniques such as factoring, using the quadratic formula, or applying numerical methods can help identify these roots, which are crucial for understanding the behavior of polynomial functions.