An absolute value of a number is its distance from zero on the number line. To write an absolute value, use bars (e.g. |5| = 5). To solve an absolute value equation, separate it into two cases - one where the expression inside the bars is positive and one where it is negative. Then solve each case separately and check the solutions. Basic graphs of absolute value functions form a V-shape, with restrictions so the y-values are always greater than or equal to 0. Shifting or stretching transformations can be applied.