What are arrays used for?

"Rarely do we ever deal with a single piece of data in a program. Instead, most data is made up of a collection of similar elements. A program to compute grades would be designed to operate on an entire roster of students. Scientific data represents a collection of many different samples or measurements. A bank maintains and processes many different accounts, etc. Arrays are a way to collect similar pieces of data together in an ordered collection . The pieces of data stored in an array are referred to as elements and are stored in an ordered manner. That is, there is a “first” element, “second” element, etc. and a “last” element. Though the elements are ordered, they are not necessarily sorted in any particular manner. Instead, the order is usually determined by the order in which you place elements into the array."