Attacks of Opportunity and Movement

Quoth the PHB:

If you move within or out of a threatened area, you usually provoke an attack of opportunity. If all you do is move (not run) during your turn, the space that you start out in is not considered threatened,, and therefore enemies do not get attacks of opportunity against you when you move from that space. If you move into another threatened space, enimed do get attacks of opportunity for your leavign the first threatened space. In addition, if your entire move for the round is 5 feet (a 5-foot step), enemies do not get attacks of opportunity for your moving.