Bathing the whole body without leaving any dry spot when in the state of major impurity or for women, at the and of menstruation or at the and of their after-birth bleeding period, is called ghusl (major ritual ablution, bath or Ghusl Janabat). It is obligatory in the above said situations, and it is act to take ghusl on the occasion of the Friday Assembly Prayer (Salat-ul Jum'a) or Festival Prayers (salat-ul-Eid), or before putting on the seamless garment (ihram) which is worn by pilgrims in Makka al Mukarramah for the major pilgrimage (Hajj) and Minor pilgrimage ('Umra).

The Obligatory Acts Of Ghusl Are There
1- Drawing water into the mouth and gargling once,
2- Sniffing water into the nostrils and cleansing the nostrils well once,
3- Bathing the entire body once, in such manner that there remains no dry spot.
How To Make Ghusl In A Perfect Way
We say the formula of Bismillah and make the intention to perform ghusl "I intend to make ghusl!" We wash our hands well and clean any dirtiness from our body.
We then make a minor ritual ablution as for ritual prayer. While making the ablution, we take plenty of water into the mouth and gargle, and the nostrils and blow the nose to cleanse the mouth and nostrils well.
We pour water three times over the head first, then three times over the right shoulder and again three times over the left shoulder, each time rubbing well the entire body. Water in this process must reac each and ever part of the entire body in the order that there doesn't reaming a single dry spot.
Those Devotions We Are Not Allowed To Perform Without Having Ritual Bath
1- We can not perform a ritual prayer,
2- We can not touch the Noble Qur'an or any verse of the Noble Qur'an
3- We can not read the Noble Qur'an,
4- We can not go around (circumambulate) the Holy Kaaba,
5- We can not enter the mosque (mejid) unless we are forced to do so (in emergency).