From what I read/understand, the 'self' parameter is similiar to 'this'.

Is that true?

If its optional, what would you do if self wasnt' passed into the method?

Yes, it's used in similar ways. Note that it's a positional parameter and you can call it what you want; however there is a strong convention to call it self (not this or anything else). Some positional parameter must be there for a usable instance method; it is not optional.