I don't know much about computers. :o
Parentheses () are side notes, in a sense. They are information that can be left out of the sentence. A writer may chose to use them, though, to clear confusion or make a simple point. For example a person may say "I have a pig as a pet (Seeing as I live on a farm, that's not unusual)" Parentheses may also be used for citations.
Quotation marks "" are used for just that, quoting a person or text. This means that you are not stating it, but rather, another is. It may also be used in cases you lack a better word in a situation. For example, I may quote "I have a pig as a pet".
There you are. c: