I would like to share a fantastic page on Purities & Impurities - درجات نقاء و الشوائب in Islam, which covers the basic topics of purities and impurities in Islam.
Topics include, fardh (obligatory acts) of wudhu - partial ablution. The Sunnah method of wudhu, along with things which break wudhu.
Fardh of ghusl - bath, the Sunnah method of ghusl, a person who needs to take a bath, and occasions of Sunnah ghusl, purifying impurities, the method of istinga, fardh of tayammum - dry ablution using sand or dust and matters which break tayammum.
Read more »