Functions Everywhere

Your phone's autocorrect is a function: input a misspelled word, output a correction. A vending machine is a function: input a code, output a snack. Tax brackets define a function from income to tax owed. Every cause-and-effect relationship can be modeled as a function.

In programming, functions are literally called functions. A block of code takes arguments (inputs), runs a procedure, and returns a result (output). The mathematical concept transferred directly into computer science, making functions one of the most universal ideas in both fields.