What is the line of succession for rulers in Saudi Arabia?

King Fahd ibn Abdulaziz of Saudi Arabia died today, August 1, 2005, after ruling Saudi Arabia for 23 years.

In making the annoucement on Saudi state television, Information Minister Iyad bin Amin Madani also announced that King Fahd would be succeeded by Crown Prince Abdullah bin Abdulaziz Al Saud, his half-brother. Why didn't one of King Faud's sons succeed him?

The Saudi leadership is voted on by the members of the royal family, of which there are currently about 6,000. Since the founding of Saudi Arabia in 1932 and the election of King Ibn Saud, the country has always been ruled by a member of the al-Saud family. After King Ibn Saud's death, succession has passed on to five of his sons:

The family usually picks a successor, named the Crown Prince, long before the current king dies, and in the case of both King Fahd and King Abdullah, they may rule behind the scenes due to illness of their predecessor (King Abdullah had been ruling in King Fahd's name since Fahd suffered a stroke in 1995.)

This article on Slate.com, from 28 Sep 2001, has a good recap of the Saudi Royal family. It is interesting to note that Bryan Curtis, the author of the article, claims "Royal-family watching is an even more difficult art than Kremlin watching was during the Cold War."