The Four Faraaidh of Wudhu
There are four Faraaidh acts for Wudhu to be complete: they are all compulsory.
a. Washing the face from the forehead to the lower portion of the chin and from the lobe of one ear to the lobe of the other; this must be done once.
b. Washing both arms, including the elbow, once.
c. Making Masah (that is, to pass a wet hand over a dry area) of a quarter of the head once.
d. Washing both feet, including the ankles, once.
If any of these Faraaidh is left out, the Wudhu is incomplete. If any portion of the body mentioned above is left dry, the Wudhu will be invalid.
Copied from "AL-Usataadh"