Asalam o Alaikum!!
The three Faraa'ids (compulsory acts) of Ghusl are:
1. To rinse the mouth in such a manner that water reaches the entire mouth.
2. To rinse the nostrils up to the ending of the fleshy part.
3. To completely wet the whole body. When one performs these Faraa'id intentionally or unintentionally Ghusl will be valid.
Ghusl is recommended in the following cases:
- Before going to Jummah Congregational (Friday Prayer).
- Before going to Eid Prayers (Muslim annual feast prayers).
- Before undertaking Umrah or Hajj (Pilgrimage to Makkah).
- Upon washing a corpse.
- When a disbeliever revert to Islam.