dotcomma.org: Introduction to CGI Part 3: Perl Variables

“If you know any other programming language, you know what
variables are. Furthermore, if you know other programming
languages, you will be thrilled to see how Perl variables work. If
you don’t know other programming languages – well, it’s not a
difficult concept to understand. However, a solid understanding of
variables is crucial to programming.”

“What is a Variable?
A variable is a piece of memory on your computer that holds a
specific piece of data. This data can be in the form of integers,
real numbers, characters, or strings. You can store data into the
variable and then retrieve it, display it, or modify it at any
point in your program.
For example, you may have a real number
variable that the user inputs at one point in the program, then
later in the program sales tax is added to it, then the final
result is displayed. The program is relying on the number that the
user enters to compute the final result.”