You could say kief is merely flower's potent residue, but technically it's one element of the trichome where the plant stores the majority of its cannabinoids and terpenes—AKA the stuff that gets us high. It tends to accumulate in the bottom of grinders as a powdery residue, so don't toss it! You can add it to joints or sprinkle it on packed bowls for an added kick of THC.
This website contains all the types of cannabis.
We have to ask, are you a small child?