**Elementary algebra** encompasses some of the basic concepts of

algebra, one of the main branches of

mathematics. It is typically taught to

secondary school students and builds on their understanding of

arithmetic. Whereas arithmetic deals with specified numbers, algebra introduces quantities without fixed values, known as variables. This use of variables entails a use of algebraic notation and an understanding of the general rules of the

operators introduced in arithmetic. Unlike

abstract algebra, elementary algebra is not concerned with

algebraic structures outside the realm of

real and

complex numbers.