using or operators with and without parentheses [duplicate]

This question already has an answer here:

• Why does checking a variable against multiple values with `OR` only check the first value? [duplicate] 4 answers
• Why does `a == b or c or d` always evaluate to True? [duplicate] 1 answer
• How to test multiple variables against a value? 15 answers

I'm fairly new to python/programming in general and I would like to know the affect (if any) that parentheses have when using the 'or' operator.

For example what's the difference between this:

if (x or y or z) == 3:
    return True

this:

if x or y or z == 3:
    return True

and this:

if x == 3 or y == 3 or z == 3:
    return True

I have tried using each line of code and have seen varied results making it difficult to identify what each line does. Any help would be greatly appreciated-thanks.