👉 A function is a mathematical expression that maps one or more input values to exactly one output value. It takes an input (often called a domain) and produces an output (also often referred to as a range). The result of applying a function to an input is known as its output, which can be either a number or another function (a "domain" function). For example, consider the function f(x) = x^2 - 4x + 3. This function takes the input