The document discusses modulus (absolute value) functions, including that the modulus function f(x)=|x| has a domain of all real numbers and a range of zero to infinity. It is symmetrical about the y-axis and has a sharp point at the origin. Transformations to the modulus function involve dilation by a factor a and vertical translation by an amount c. A modulus function can also be expressed as two separate functions, one for negative values of f(x) and one for positive values of f(x).