Wahabbis are like the Puritans in a way. They have a very harsh and narrow interpretation of Islam. They don't like being called Wahabbi and refer to themselves as "Salafi". It all really started with this bloke named Abdul Wahab back in Arabia some centuries ago. His own father and brother who were respected Islamic scholars preached against Abdul Wahab's distorted interpretation of Islam. Anyway, Abdul Wahab managed to get quite a few followers and caused a lot of trouble and his people banded with the Sa'ud family. When the Sa'ud clan came to power and oil was discovered on their territory they all became extremely rich and powerful and were able to export this Wahabbi version of Islam globally by funding the building of mosques, publishing Islamic literature which had a very harsh interpretation and appointing Imams (leaders of the mosque) that had a Wahabbi mentality.
Anyway, that is a very very condensed version of where these people come from. If you want to get a better picture then do check out those 2 books I recommended. I'm not a model muslim but I hate to see my religion dragged down to the gutter by these Wahabbi mofos.