Yes and no... It is typically at it's most useful after an assignment, and it's use is that it generates a value, but that doesn't necessarily mean it needs to be used in an assignment. Others have given examples, but the essential thing to remember is that the ternary operator returns a value. if does not: It is a flow-control operator.

So, where it does need to be used is where Perl would expect a value. Assignments are one common case of that.