What is a function? How do functions work? These questions and more will be answered in this section of algebra 1! Functions are the basis for just about everything you'll learn in algebra 1, between solving, graphing, and analyzing them. A function is a relationship between two variables in which every input corresponds to exactly one output. Functions are like mathematical machines to manipulate numbers, which makes them super useful in modeling real world phenomena, manipulating numbers, and representing equations. Fiveable's free guides will teach you everything you need to know about functions so you can succeed in math!