There are two ways of wiping the head in Wudu: 1- After wetting the hands in water, you place them at the front of the head and wipe the head until you reach the back of the head, then you bring them back to the front of the head. 2- Wiping the whole head, but in the direction of the hair only, so that the hair is not changed or messed up.

1. There are 14 pillars of prayer and there are 8 obligatory parts of prayer. There are many Sunnah acts of prayer, both words and actions. 2. The difference between a pillar and an obligatory part is that a pillar cannot be waived, whether one omits it deliberately or by mistake, rather it must be done. An obligatory part is waived if one forgets, and it can be compensated for by doing the prostration of forgetfulness (sujud as-sahw). Learn more in the detailed answer.