What is tribal anyway?

So what is tribal council anyway? I'm not sure at this point. It feels awesome to go 5 for 5 in immunity challenges, because I have had time to build alliances without having to test them at tribal. This also means that it is hard to trust others because I have not seen that trust personified in votes yet. I'm just hoping I can ride this winning streak to the merge, and then have these bonds take me to the end. The strategy is simple and sweet ... and it just might work...