A cubic equation is a polynomial equation of the form ax^3 + bx^2 + cx + d = 0, where a, b, c, and d are constants, and a is not zero. The highest exponent, which is 3, indicates that the equation is cubic. These equations can have one real root and two complex roots, or three real roots, depending on the values of the coefficients. Cubic equations can be solved using various methods, including factoring, synthetic division, or applying the Cubic Formula. They are important in various fields such as physics, engineering, and economics for modeling relationships and predicting outcomes.