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.