What is the Islamic ruling on Fatwas and how should those Fatwas be treated in the light of Islam?

Since the dawn of our creation, mankind has a innate curiosity, and hence we tend to question about our surroundings. During my search on the topic (which requires an Islamic view point), however, when I went to through the forums such Islam Stack Exchange and Islam Helpline . I found out that although some answers did contain Hadis and Sunnah and some answers even Quranic Verses, most of them contained Fatwas over Fatwas from all different schools of thought. So I was wondering: What is the Islamic ruling on Fatwas and how should those Fatwas be treated in the light of Islam?