A comment is an explanation added to code by the programmer in order to clarify its purpose. Comments are used to explain why code was written the way it was or to clarify what each individual piece of a complicated block of code is for.
Comments are enclosed in braces { } and may appear anywhere. They may appear in the middle of a statement without affecting the execution of that statement. A common use of comments is to describe the purpose of each parameter in a long function call:
ZPipe(x[0], y[0] { First endpoint for pipe },
8 { Number of vertices },
176, 239 { Very dark gray to very light gray },
24 { Width of pipe in pixels });