The Book of Ruby

Chapter 11. Symbols

Many newcomers to Ruby are confused by symbols. A symbol is an identifier whose first character is a colon (:), so :this is a symbol and so is :that. Symbols are, in fact, not at all complicated—and, in certain circumstances, they may be extremely useful, as you will see shortly.

Let’s first be clear about what a symbol is not: It is not a string, it is not a constant, and it is not a variable. A symbol is, quite simply, an identifier with no intrinsic meaning other than its own name. Whereas you might assign a value to a variable like this . . .

name = "Fred"

you would not assign a value to a symbol:

:name = "Fred"    # Error!

The value ...