What really is Ni?

I have been surfing on all socionics-related sources of information and I couldn't find a description of Ni (hint, especially in INFps) that I could wrapy my mind around. I'm either too stupid, or they all follow the same over-complicated pattern of explanation. So if you have your own ways of explaining Ni, use of Ni and experiences involving it, then feel free to share with me on here.

Really, any description that doesn't make Ni out to be superpowers, voodoo magic or just symtpoms of depression will help me greatly.