Although there are many ways of attachment nodes and the knots, basically they can be classified into two groups: those which are used for tying a rope to a fixed object and the ones that are used to connect the two ropes, preferably of different thickness.
Whichever knot tying, rope has two parts in relation to the node - a dead end, where you can not handle, and the living end. The loop between the two ends can be upper (living end goes over the dead) or lower (a live dead end goes below).