"A variable is the fundamental building block of any programming languages. Think of a variable as a container which can be used to store data; this data is used in different places in your Perl program. A variable can store both numeric and non-numeric data, and the contents of a variable can be altered during program execution. Finally, variables can be compared with each other, and you--the programmer--can write program code that performs specific actions on the basis of this comparison."
"Every language has different types of variables--however, for the moment, we're going to concentrate on the simplest type, referred to in Perl as "scalar variables". A scalar variable can hold any type of value--integer, text string, floating-point number--and is usually preceded by a dollar sign."