Ghusl has 3 Faraiz (Obligatory Acts):
1. Rinsing the mouth thoroughly. Gargling should be done too, as it is Sunnah, unless the person is fasting.
2. Sniffing water into the nose; ensuring that the water reaches the soft inner part of the nose. However, a fasting individual should not take in water too far up the nose or gargle while rinsing the mouth, as this could cause water to enter the throat and invalidate the fast.
3. Pouring water over the entire body; ensuring that no spot, even as small as a hair, remains dry.
Fulfilling these three obligatory acts completes the wajib (obligatory) ghusl.