Perl has three basic data types: scalars, arrays, and hashes.

Scalars are essentially simple variables. They are preceded by a dollar sign ($). A scalar is either a number, a string, or a reference. (A reference is a scalar that points to another piece of data. References are discussed later in this chapter.) If you provide a string in which a number is expected or vice versa, Perl automatically converts the operand using fairly intuitive rules.

Arrays are ordered lists of scalars accessed with a numeric subscript (subscripts start at 0). They are preceded by an “at” sign (@).

Hashes are unordered sets of key/value pairs accessed with the keys as subscripts. They are preceded by a percent sign (%).