This document discusses relations and functions in mathematics. It defines a relation as a correspondence between two things represented as a set of ordered pairs, with the first element called the domain or independent variable and the second called the range or dependent variable. It states that for a relation to be a function, each element in the domain can only be paired with one element in the range, otherwise it would be "cheating". It also lists different ways relations and functions can be represented, including tables, mapping diagrams, graphs, and ordered pairs.