Quadratic equations are equations of the form ax^2 + bx + c = 0, where a ≠ 0. They are called quadratic because the highest exponent is 2. The standard form is ax^2 + bx + c = 0. Quadratic equations can be solved using the quadratic formula. Some examples of where quadratic equations are used include calculating time, velocity, distance, height, area, length, speed, cost, and benefits.