Single Quotes

[Han]

(10-21-2014 09:31 PM)Helge Gabert Wrote:  Look under QUOTE (catalog help).

The quotes are used to return an expression unevaluated - - useful if you would like to store, say, an algebraic expression (as is) in some variable and use it later (e.g., in a program).

As already mentioned, they are used to denote algebraic objects which you do not wish to be evaluated. Within a program, it's a means to pass functions as arguments.