What are major ritual impurity and minor ritual impurity, and how is ritual bathing (ghusl) performed for each?

Imam Nawawi said that hadath (ritual impurity) applies to that which necessitates ablution (wudu) and that which necessitates a full ritual bath (ghusl). There is a major hadath and a minor hadath. The major hadath is that which necessitates ghusl, such as janabah (state of ritual impurity following sexual intercourse or seminal emission), menstruation, and post-childbirth bleeding. This is removed only by ghusl. As for the minor hadath, it does not necessitate ghusl; wudu suffices for it.