There are three obligatory elements of Ghusl. They are:
To rinse the mouth making sure that every part of the mouth from the beginning of the lips up to the throat is properly rinsed. Water must reach the gaps between the teeth, gums, all the sides of the tongue and the back of the throat. If you are not fasting then you must gargle so that the water reaches all parts. If anything is stuck in the teeth like strands of meat, then this must be removed, unless if by removing this, it would cause severe pain or damage.

To clean the nostrils out with water, sucking up water into both nostrils, making sure it reaches the bone, so that not even a hair or its equivalent size remains dry, otherwise the bath will not count. If the nose is pierced then it is necessary that the water reach the hole. Dried mucus that is in the nostrils must be removed.

The complete washing of every part of the body, up to and including the soles of the feet. If one spot is left dry, or even one strand of hair is dry, then the Ghusl will not be complete.