Function: A function is a special type of algebraic representation that relates each input value (x) to exactly one output value (y). It can be thought of as a machine that takes in inputs and produces corresponding outputs.
Equation: An equation is an algebraic representation that states two expressions are equal. It involves an equal sign (=) and can be solved to find the values of variables that make it true.
Expression: An expression is a combination of numbers, variables, and operations without an equal sign. It represents a quantity or calculation but does not make any claims about equality.