Index (indices) in Maths is the power or exponent which is raised to a number or a variable. For example, in number 2^4, 4 is the index of 2 and 2 is referred to as the base. The plural form of index is indices. Indices are used to display how many times a number has been multiplied by itself. They can also be used to represent roots and fractions, such as the square root. In this lesson, you will learn the rules/laws of indices and use the rules to manipulate certain expressions into equivalent expressions. Additionally, roots and exponents are closely linked, because roots represent a logical inverse of exponents. You will also learn more about roots.