What does the `&` mean in the following ruby syntax?

Question

In the following ruby example, what does the & represent? Is it along the line of += in a loop?

payments.sum(&:price)
         


        

Answer 1

"If the last argument to a method is preceded by an ampersand, Ruby assumes that it is a Proc object. It removes it from the parameter list, converts the Proc object into a block, and associates it with the method."

From Programming Ruby: The Pragmatic Programmers' Guide

Read more about it in this article.